Buffer status reporting in a mobile communication system

ABSTRACT

An invention relates to methods for transmitting a buffer status report (BSR) in a mobile communication system, more particularly to the definition of rules for triggering, generating and transmitting BSRs. The invention also relates to a data transmission method utilizing new rules to decide data of which radio bearers is transmitted within a given transmission time interval. Moreover, the invention relates to scheduling method for radio resources that is taking into account additional scheduling-relevant information from the buffer status reporting and/or data transmission method. To avoid unnecessary grants from the network and to suggest an advanced handling of data transmissions the invention suggests a buffer status reporting and data transmission schemes that take into account the scheduling mode of data of radio bearers pending for transmission to decide whether to report on it in a buffer status report, respectively, whether to multiplex the data to a transport block for transmission.

FIELD OF THE INVENTION

The invention relates to methods for transmitting a buffer status reportby a communication node in a mobile communication system, and moreparticularly to the definition of rules for triggering, generating andtransmitting buffer status reports. Furthermore, the invention is alsorelated to an data transmission method utilizing a new set of rules todecide data of which radio bearers is to be transmitted within a giventransmission time interval. Moreover, the invention also relates toscheduling radio resources within a mobile communication system that istaking into account additional scheduling-relevant information from thebuffer status reporting and/or data transmission method. The inventionalso relates to the implementation/performance of these methods in/byhardware, i.e. apparatuses, and their implementation in software.

TECHNICAL BACKGROUND

Long Term Evolution (LTE)

Third-generation mobile systems (3G) based on WCDMA (Wideband CodeDivision Multiple Access) radio-access technology are being deployed ona broad scale all around the world. A first step in enhancing orevolving this technology entails introducing High-Speed Downlink PacketAccess (HSDPA) and an enhanced uplink, also referred to as High SpeedUplink Packet Access (HSUPA), giving a radio-access technology that ishighly competitive.

However, knowing that user and operator requirements and expectationswill continue to evolve, the 3GPP (3^(rd) Generation PartnershipProject) has begun considering the next major step or evolution of the3G standard to ensure the long-term competitiveness of 3G. The 3GPPlaunched a Study Item “Evolved UTRA and UTRAN” (abbreviated E-UTRA andE-UTRAN) also referred to as long-term evolution (LTE). The study willinvestigate means of achieving major leaps in performance in order toimprove service provisioning and reduce user and operator costs.

It is generally assumed that there will be a convergence toward the useof Internet Protocols (IP), and all future services will be carried ontop of IP. Therefore, the focus of the evolution is on enhancements tothe packet-switched (PS) domain.

The main objectives of the evolution are to further improve serviceprovisioning and reduce user and operator costs as already mentioned.

More specifically, some key performance and capability targets for thelong-term evolution are

Significantly higher data rates compared to HSDPA and HSUPA: envisionedtarget peak data rates of more than 100 Mbps over the downlink and 50Mbps over the uplink

Improved coverage: high data rates with wide-area coverage

Significantly reduced latency in the user plane in the interest ofimproving the performance of higher layer protocols (for example, TCP)as well as reducing the delay associated with control plane procedures(for instance, session setup)

Greater system capacity: threefold capacity compared to currentstandards.

One other key requirement of the long-term evolution is to allow for asmooth migration to these technologies.

LTE Architecture

In FIG. 1 an overview of a 3GPP LTE mobile communication network isshown. The network consists of different network entities that arefunctionally grouped into the Evolved Packet Core (EPC), the RadioAccess Network (RAN) and the User Equipments (UEs) or mobile terminals.

The radio access network is responsible for handling all radio-relatedfunctionality inter alia including scheduling of radio resources. Theevolved packet core may be responsible for routing calls and dataconnections to external networks.

The LTE network is a “two node architecture” consisting of servinggateways (SGW) and enhanced base stations, so-called eNode Bs(abbreviated eNB or eNode B). The serving gateways will handle evolvedpacket core functions, i.e. routing calls and data connections toexternal networks, and also implement radio access network functions.Thus, the serving gateway may be considered as to combine functionsperformed by GGSN (Gateway GPRS Support Node) and SGSN (Serving GPRSSupport Node) in today's 3G networks and radio access network functionsas for example header compression, ciphering/integrity protection. TheeNode Bs may handle functions as for example Radio Resource Control(RRC), segmentation/concatenation, scheduling and allocation ofresources, multiplexing and physical layer functions.

A mobile communication network is typically modular and it is thereforepossible to have several network entities of the same type. Theinterconnections of network elements are defined by open interfaces. UEscan connect to an eNode B via the air interface or Uu. The eNode Bs havea connection to a serving gateway via the S1 interface. Two eNode Bs areinterconnected via the X2 interface.

Both 3GPP and Non-3GPP integration may be handled via the servinggateway's interface to the external packet data networks (e.g.Internet).

QoS Control

Efficient Quality of Service (QoS) support is seen as a basicrequirement by operators for LTE. In order to allow best in class userexperience, while on the other hand optimizing the network resourceutilization, enhanced QoS support should be integral part of the newsystem.

Aspects of QoS support is currently being under discussion within 3GPPworking groups. Essentially, the QoS design for System ArchitectureEvolution (SAE)/LTE is based on the QoS design of the current UMTSsystem reflected in 3GPP TR 25.814, “Physical layer aspects for evolvedUniversal Terrestrial Radio Access (UTRA)”, v.7.1.0 (available athttp://www.3gpp.org and incorporated herein by reference). The agreedSAE Bearer Service architecture is depicted in FIG. 2. The definition ofa bearer service as given in 3GPP TR 25.814 may still be applicable:

“A bearer service includes all aspects to enable the provision of acontracted QoS. These aspects are among others the control signaling,user plane transport and QoS management functionality”.

In the new SAE/LTE architecture the following new bearers have beendefined: the SAE Bearer service between the mobile terminal (UserEquipment—UE) and the serving gateway, the SAE Radio Bearer on the radioaccess network interface between mobile terminal and eNode B as well asthe SAE Access Bearer between the eNode B and the serving gateway.

The SAE Bearer Service provides:

QoS-wise aggregation of IP end-to-end-service flows;

IP header compression (and provision of related information to UE);

User Plane (UP) encryption (and provision of related information to UE);

if prioritized treatment of end-to-end-service signaling packets isrequired an additional SAE Bearer Service can be added to the default IPservice;

provision of mapping/multiplexing information to the UE;

provision of accepted QoS information to the UE.

The SAE Radio Bearer Service provides:

transport of the SAE Bearer Service data units between eNode B and UEaccording to the required QoS;

linking of the SAE Radio Bearer Service to the respective SAE BearerService.

The SAE Access Bearer Service provides:

transport of the SAE Bearer Service data units between serving gatewayand eNode B according to the required QoS;

provision of aggregate QoS description of the SAE Bearer Service towardsthe eNode B;

linking of the SAE Access Bearer Service to the respective SAE BearerService.

In 3GPP TR 25.814 a one-to-one mapping between an SAE Bearer and an SAERadio Bearer. Furthermore there is a one-to-one mapping between a radiobearer (RB) and a logical channel. From that definition it follows thata SAE Bearer, i.e. the corresponding SAE Radio Bearer and SAE AccessBearer, is the level of granularity for QoS control in an SAE/LTE accesssystem. Packet flows mapped to the same SAE Bearer receive the sametreatment.

For LTE there will be two different SAE bearer types: the default SAEbearer with a default QoS profile, which is configured during initialaccess and the dedicated SAE bearer (SAE bearers may also be referred toas SAE bearer services) which is established for services requiring aQoS profile which is different from the default one.

The default SAE bearer is an “always on” SAE bearer that can be usedimmediately after LTE_IDLE to LTE_ACTIVE state transition. It carriesall flows which have not been signaled a Traffic Flow Template (TFT).The Traffic Flow Template is used by serving gateway to discriminatebetween different user payloads. The Traffic Flow Template incorporatespacket filters such as QoS. Using the packet filters the serving gatewaymaps the incoming data into the correct PDP Context (Packet DataProtocol Context). For the default SAE bearer, several service dataflows can be multiplexed. Unlike the Default SAE Bearer, the DedicatedSAE Bearers are aimed at supporting identified services in a dedicatedmanner, typically to provide a guaranteed bit-rate. Dedicated SAEbearers are established by the serving gateway based on the QoSinformation received in Policy and Charging Control (PCC) rules fromevolved packet core when a new service is requested. A dedicated SAEbearer is associated with packet filters where the filters match onlycertain packets. A default SAE bearer is associated with “match all”packet filters for uplink and downlink. For uplink handling the servinggateway builds the Traffic Flow Template filters for the dedicated SAEbearers. The UE maps service data flows to the correct bearer based onthe Traffic Flow Template, which has been signaled during bearerestablishment. As for the default SAE Bearer, also for the dedicated SAEBearer several service data flows can be multiplexed.

The QoS Profile of the SAE bearer is signaled from the serving gatewayto the eNode B during the SAE bearer setup procedure. This profile isthen used by the eNode B to derive a set of Layer 2 QoS parameters,which will determine the QoS handling on the air interface. The Layer 2QoS parameters are input the scheduling functionality. The parametersincluded in the QoS profile signaled on S1 interface from servinggateway to eNode B are currently under discussion. Most likely thefollowing QoS profile parameters are signaled for each SAE bearer:Traffic Handling Priority, Maximum Bit-rate, Guaranteed Bit-rate. Inaddition, the serving gateway signals to the eNode B the Allocation andRetention Priority for each user during initial access.

Uplink Access Scheme for LTE

For uplink transmission, power-efficient user-terminal transmission isnecessary to maximize coverage. Single-carrier transmission combinedwith FDMA (Frequency Division Multiple Access) with dynamic bandwidthallocation has been chosen as the evolved UTRA uplink transmissionscheme. The main reason for the preference for single-carriertransmission is the lower peak-to-average power ratio (PAPR), comparedto multi-carrier signals (OFDMA—Orthogonal Frequency Division MultipleAccess), and the corresponding improved power-amplifier efficiency andassumed improved coverage (higher data rates for a given terminal peakpower). During each time interval, Node B assigns users a uniquetime/frequency resource for transmitting user data thereby ensuringintra-cell orthogonality. An orthogonal access in the uplink promisesincreased spectral efficiency by eliminating intra-cell interference.Interference due to multipath propagation is handled at the base station(Node B), aided by insertion of a cyclic prefix in the transmittedsignal.

The basic physical resource used for data transmission consists of afrequency resource of size BW_(grant) during one time interval, e.g. asub-frame of 0.5 ms, onto which coded information bits are mapped. Itshould be noted that a sub-frame, also referred to as transmission timeinterval (TTI), is the smallest time interval for user datatransmission. It is however possible to assign a frequency resourceBW_(grant) over a longer time period than one TTI to a user byconcatenation of sub-frames.

The frequency resource can either be in a localized or distributedspectrum as illustrated in FIG. 3 and FIG. 4. As can be seen from FIG.3, localized single-carrier is characterized by the transmitted signalhaving a continuous spectrum that occupies a part of the total availablespectrum. Different symbol rates (corresponding to different data rates)of the transmitted signal imply different bandwidths of a localizedsingle-carrier signal.

On the other hand, as shown in FIG. 4, distributed single-carrier ischaracterized by the transmitted signal having a non-continuous(“comb-shaped”) spectrum that is distributed over system bandwidth. Notethat, although the distributed single-carrier signal is distributed overthe system bandwidth, the total amount of occupied spectrum is, inessence, the same as that of localized single-carrier. Furthermore, forhigher/lower symbol rate, the number of “comb-fingers” isincreased/reduced, while the “bandwidth” of each “comb finger” remainsthe same.

At first glance, the spectrum in FIG. 4 may give the impression of amulti-carrier signal where each comb-finger corresponds to a“sub-carrier”. However, from the time-domain signal-generation of adistributed single-carrier signal, it should be clear that what is beinggenerated is a true single-carrier signal with a corresponding lowpeak-to-average power ratio. The key difference between a distributedsingle-carrier signal versus a multi-carrier signal, such as e.g. OFDM(Orthogonal Frequency Division Multiplex), is that, in the former case,each “sub-carrier” or “comb finger” does not carry a single modulationsymbol. Instead each “comb-finger” carries information about allmodulation symbols. This creates a dependency between the differentcomb-fingers that leads to the low-PAPR characteristics. It is the samedependency between the “comb fingers” that leads to a need forequalization unless the channel is frequency-non-selective over theentire transmission bandwidth. In contrast, for OFDM equalization is notneeded as long as the channel is frequency-non-selective over thesub-carrier bandwidth.

Distributed transmission can provide a larger frequency diversity gainthan localized transmission, while localized transmission more easilyallows for channel-dependent scheduling. Note that, in many cases thescheduling decision may decide to give the whole bandwidth to a singleUE to achieve high data rates.

UL Scheduling Scheme for LTE

The uplink scheme allows for both scheduled access, i.e. controlled byeNode B, and contention-based access.

In case of scheduled access the UE is allocated a certain frequencyresource for a certain time (i.e. a time/frequency resource) for uplinkdata transmission. However, some time/frequency resources can beallocated for contention-based access. Within these time/frequencyresources, UEs can transmit without first being scheduled. One scenariowhere UE is making a contention-based access is for example the randomaccess, i.e. when UE is performing initial access to a cell or forrequesting uplink resources.

For the scheduled access Node B scheduler assigns a user a uniquefrequency/time resource for uplink data transmission. More specificallythe scheduler determines

which UE(s) that is (are) allowed to transmit,

which physical channel resources (frequency),

for how long the resources may be used (number of sub-frames)

Transport format (Transport Block Size (TBS) and Modulation CodingScheme (MCS)) to be used by the mobile terminal for transmission

The allocation information is signaled to the UE via a scheduling grant,sent on the so-called L1/L2 control channel. For simplicity, thisdownlink channel is referred to the “uplink grant channel” in thefollowing. A scheduling grant message contains at least informationwhich part of the frequency band the UE is allowed to use, the validityperiod of the grant, and the transport format the UE has to use for theupcoming uplink transmission. The shortest validity period is onesub-frame. Additional information may also be included in the grantmessage, depending on the selected scheme. Only “per UE” grants are usedto grant the right to transmit on the Uplink Shared Channel UL-SCH (i.e.there are no “per UE per RB” grants). Therefore the UE needs todistribute the allocated resources among the radio bearers according tosome rules, which will be explained in detail in the next section.Unlike in HSUPA there is no UE based transport format selection. Thebase station (eNode B) decides the transport format based on someinformation, e.g. reported scheduling information and QoS information,and UE has to follow the selected transport format. In HSUPA Node Bassigns the maximum uplink resource and UE selects accordingly theactual transport format for the data transmissions.

Uplink data transmissions are only allowed to use the time-frequencyresources assigned to the UE through the scheduling grant. If the UEdoes not have a valid grant, it is not allowed to transmit any uplinkdata. Unlike in HSUPA, where each UE is always allocated a dedicatedchannel there is only one uplink data channel shared by multiple users(UL SCH) for data transmissions.

To request resources, the UE transmits a resource request message to theNode B. This resources request message could for example containinformation on the buffer status, the power status of the UE and someQuality of Services (QoS) related information. This information, whichwill be referred to as scheduling information, allows Node B to make anappropriate resource allocation. Throughout the document it's assumedthat the buffer status is reported for every radio bearer. Of courseother configurations for the buffer status reporting are also possible.

Since the scheduling of radio resources is the most important functionin a shared channel access network for determining Quality of Service,there are a number of requirements that should be fulfilled by theuplink scheduling scheme for LTE in order to allow for an efficient QoSmanagement (see 3GPP RAN WG#2 Tdoc. R2-R2-062606, “QoS operatorrequirements/use cases for services sharing the same bearer”, byT-Mobile, NTT DoCoMo, Vodafone, Orange, KPN; available athttp://www.3gpp.org/and incorporated herein by reference):

The UL scheduling scheme for LTE should provide a finer network-basedQoS control than what is supported in UMTS Release 6 (HSUPA)

Starvation of low priority services should be avoided

Clear QoS differentiation for radio bearers/services should be supportedby the scheduling scheme

The UL reporting should allow fine granular buffer reports (e.g. perradio bearer or per radio bearer group) in order to allow the eNode Bscheduler to identify for which Radio Bearer/service data is to be sent.

It should be possible to change the priorities used in the UL schedulingdecision of the UE dynamically—based on operator requirements

It should be possible to make clear QoS differentiation between servicesof different users

It should be possible to provide a minimum bit-rate per radio bearer

As can be seen from above list one essential aspect of the LTEscheduling scheme is to provide mechanisms with which the operator cancontrol the partitioning of its aggregate cell capacity between theradio bearers of the different QoS classes. The QoS class of a radiobearer is identified by the QoS profile of the corresponding SAE bearersignaled from serving gateway to eNode B as described before. Anoperator can then allocate a certain amount of its aggregate cellcapacity to the aggregate traffic associated with radio bearers of acertain QoS class.

The main goal of employing this class-based approach is to be able todifferentiate the treatment of packets depending on the QoS class theybelong to. For example, as the load in a cell increases, it should bepossible for an operator to handle this by throttling traffic belongingto a low-priority QoS class. At this stage, the high-priority trafficcan still experience a low-loaded situation, since the aggregateresources allocated to this traffic is sufficient to serve it. Thisshould be possible in both uplink and downlink direction.

One benefit of employing this approach is to give the operator fullcontrol of the policies that govern the partitioning of the bandwidth.For example, one operator's policy could be to, even at extremely highloads, avoid starvation of traffic belonging to its lowest priority QoSClass. The avoidance of starvation of low priority traffic is one of themain requirements for the UL scheduling scheme in LTE. In current UMTSRelease 6 (HSUPA) scheduling mechanism the absolute prioritizationscheme may lead to starvation of low priority applications. E-TFCselection (Enhanced Transport Format Combination selection) is done onlyin accordance to absolute logical channel priorities, i.e. thetransmission of high priority data is maximized, which means that lowpriority data is possibly starved by high priority data. In order toavoid starvation the Node B scheduler must have means to control fromwhich radio bearers a UE transmits data. This mainly influences thedesign and use of the scheduling grants transmitted on the L1/L2 controlchannel in downlink. In the following the details of the UL rate controlprocedure in LTE is outlined.

Semi-Persistent Scheduling (SPS)

In the downlink and uplink, the scheduling eNode B dynamically allocatesresources to user equipments at each transmission time interval via theL1/L2 control channel(s) (PDCCH(s)) where the user equipments areaddressed via their specific C-RNTIs. The CRC of a PDCCH is masked withthe addressed user equipment's C-RNTI (so-called dynamic PDCCH). Only auser equipment with a matching C-RNTI can decode the PDCCH contentcorrectly, i.e. the CRC check is positive. This kind of PDCCH signalingis also referred to as dynamic (scheduling) grant. A user equipmentmonitors at each transmission time interval the L1/L2 control channel(s)for a dynamic grant in order to find a possible allocation (downlink anduplink) it is assigned to.

In addition, E-UTRAN can allocate uplink/downlink resources for initialHARQ transmissions persistently. When required, retransmissions areexplicitly signaled via the L1/L2 control channel(s). Sinceretransmissions are scheduled, this kind of operation is referred to assemi-persistent scheduling (SPS), i.e. resources are allocated to theuser equipment on a semi-persistent basis (semi-persistent resourceallocation). The benefit is that PDCCH resources for initial HARQtransmissions are saved. For details on semi-persistent scheduling, see3GPP TS 36.300, “Evolved Universal Terrestrial Radio Access (E-UTRA) andEvolved Universal Terrestrial Radio Access Network (E-UTRAN); Overalldescription; Stage 2 (Release 8)”, version 8.7.0, section 11, January2009 or 3GPP TS 36.321 “Evolved Universal Terrestrial Radio Access(E-UTRA); Medium Access Control (MAC) protocol specification (Release8)”, version 8.5.0, section 5.10 March 2009, both available athttp://www.3gpp.org and incorporated herein by reference.

One example for a service, which might be scheduled usingsemi-persistent scheduling is Voice over IP (VoiP). Every 20 ms a VoIPpacket is generated at the codec during a talk-spurt. Therefore eNode Bcould allocated uplink or respectively downlink resource persistentlyevery 20 ms, which could be then used for the transmission of Voice overIP packets. In general, semi-persistent scheduling is beneficial forservices with a predictable traffic behavior, i.e. constant bit rate,packet arrival time is periodic.

The user equipment also monitors the PDCCHs in a sub-frame where it hasbeen allocated resources for an initial transmission persistently. Adynamic (scheduling) grant, i.e. PDCCH with a C-RNTI-masked CRC, canoverride a semi-persistent resource allocation. In case the userequipment finds its C-RNTI on the L1/L2 control channel(s) in thesub-frames where the sub-frame has a semi-persistent resource assigned,this L1/L2 control channel allocation overrides the semi-persistentresource allocation for that transmission time interval and the userequipment does follow the dynamic grant. When sub-frame doesn't find adynamic grant it will transmit/receive according to the semi-persistentresource allocation.

The configuration of semi-persistent scheduling is done by RRCsignaling. For example the periodicity, i.e. PS_PERIOD, of thepersistent allocation is signaled within Radio resource Control (RRC)signaling. The activation of a persistent allocation and also the exacttiming as well as the physical resources and transport format parametersare sent via PDCCH signaling. Once semi-persistent scheduling isactivated, the user equipment follows the semi-persistent resourceallocation according to the activation SPS PDCCH every semi-persistentscheduling interval (SPS interval). Essentially the user equipmentstores the SPS activation PDCCH content and follows the PDCCH with thesignaled periodicity.

In order to distinguish a dynamic PDCCH from a PDCCH, which activatessemi-persistent scheduling, i.e. also referred to as SPS activationPDCCH, a separate identity has been introduced in LTE. Basically, theCRC of a SPS activation PDCCH is masked with this additional identitywhich is in the following referred to as SPS C-RNTI. The size of the SPSC-RNTI is also 16 bits, same as the normal C-RNTI. Furthermore the SPSC-RNTI is also user equipment-specific, i.e. each user equipmentconfigured for semi-persistent scheduling is allocated a unique SPSC-RNTI.

In case a user equipment detects a semi-persistent resource allocationis activated by a corresponding SPS PDCCH, the user equipment will storethe PDCCH content (i.e. the semi-persistent resource assignment) andapply it every semi-persistent scheduling interval, i.e. periodicitysignaled via RRC. As already mentioned, a dynamic allocation, i.e.signaled on dynamic PDCCH, is only a “one-time allocation”.

Similar to the activation of semi-persistent scheduling, the eNode Balso can deactivate semi-persistent scheduling. Semi-persistentscheduling de-allocation is signaled by SPS PDCCH with both theModulation and coding scheme field and the Resource Block Assignmentfield bits all set to ‘1’.

For semi-persistent scheduling (SPS) in LTE Release 8, ifsemi-persistent scheduling is configured and activated, it is assumedthat there is only one radio bearer set up which has data suitable forsemi-persistent scheduling. For future releases of LTE (e.g.LTE-Advanced) it is assumed that more than one radio bearer suitable forsemi-persistent scheduling can be set up, so that semi-persistentscheduling needs to deliver data of more than one radio bearer.

Buffer Status Reporting

The buffer status reporting procedure in LTE is used to provide theeNode B with information about the amount of data available fortransmission in the uplink buffers of the user equipments on a perlogical channel basis—please note that data of each radio bearer aremapped to are respective logical channel. A so-called Buffer StatusReport (BSR) is triggered, if any of the following events happen:

Uplink data, for a logical channel (i.e. of a respective radio bearer)which belongs to a Logical Channel Group (LCG), becomes available fortransmission in the RLC (Radio Link Control) or PDCP (Packet DataConvergence Protocol) layer. Furthermore, the data belongs to a logicalchannel with higher priority than the priorities of the logical channelsfor which data is already available for transmission. A “Regular BSR” istriggered in this case.

Uplink resources are allocated and the number of padding bits in thetransport block (MAC PDU) is equal to or larger than the size of theBuffer Status Report MAC control element. A “Padding BSR” is triggeredin this case.

A serving cell change occurs. A “Regular BSR” is triggered in this case.

Furthermore, a (periodic) buffer status report is also triggered by theexpiry of the following timers:

when the RETX_BSR_TIMER expires and the UE has data available fortransmission a “Regular BSR” is triggered.

when PERIODIC_BSR_TIMER expires, a “Periodic BSR” is triggered.

If a “Regular BSR” or “Padding BSR” was triggered and more than onelogical channel group (LCG) has data available for transmission in thereferring transmission time interval a so-called “Long BSR” will be sentwhich is reporting on the buffer status for all four LCGs. In case onlyone LCG has data available, a so-called “Short BSR” including only thedata of this LGC will be sent.

If a “Padding BSR” was triggered, it depends on the amount of paddingbits available in the referring transmission time interval, what kind ofbuffer status report will be sent. If the amount of padding bits islarge enough to accommodate a Long BSR, this type of BSR will be sent.

In case that more than one LCG has data in the buffer to report and theamount of padding bits does not allow a Long BSR but there are enoughpadding bits to send a Short BSR, a so-called “Truncated BSR” is sent.The Truncated BSR has the same format of the Short BSR and reports theLCG that includes the logical channel that has data available fortransmission and that has the highest priority.

In case there is only one LCG with data to report and padding bits allowfor a Short BSR, a Short BSR is send.

If the buffer status reporting procedure determines that currently abuffer status report has been triggered and the UE has uplink resourcesallocated for a new transmission in the current transmission timeinterval a BSR MAC control element is created for inclusion in thecurrent MAC PDU, i.e. the buffer status report is multiplexed with theuplink (user) data. The PERIODIC_BSR_TIMER is restarted every time a BSRis sent, except for situations where a “Truncated BSR” is transmitted.

In case there are no uplink resources allocated for the currenttransmission time interval and a “Regular BSR” was triggered, ascheduling request (SR) is triggered in order to request uplinkresources for transmitting the buffer status report.

In one MAC PDU, there can be at most one MAC BSR control element forsending a buffer status report, even if multiple BSR events occurred.The “Regular BSR” and the “Periodic BSR” have precedence over the“Padding BSR”. The RETX_BSR_TIMER is restarted upon reception of a grantfor transmission of the buffer status report.

In case the uplink grant can accommodate all pending data available fortransmission but is not sufficient to additionally accommodate the BSRMAC control element, all triggered BSRs are cancelled. Furthermore, alltriggered BSRs are cancelled when a buffer status report is included ina MAC PDU for transmission.

Scheduling Requests

The Scheduling Request (SR) is used for requesting resources for a newtransmission, e.g. MAC PDU. As indicated above, control information,like a buffer status report, and user data are multiplexed within theMAC PDU. When a scheduling request is triggered, it is consideredpending. As long as one scheduling request is pending, the userequipment first checks, if there are uplink resources available on theuplink shared channel (UL-SCH) for a transmission in this transmissiontime interval. In this case all pending scheduling requests arecancelled.

If there are no uplink resources on the UL-SCH within the nexttransmission time interval but the user equipment has a valid PUCCHresource for scheduling requests configured for this transmission timeinterval (and the transmission time interval is not part of ameasurement gap), the user equipment transmits a scheduling request onthe PUCCH and the SR_COUNTER is incremented.

If SR_COUNTER=SR_TRANS_MAX or if there are no valid PUCCH resources inany transmission time interval, all pending scheduling requests arecancelled and a Random Access procedure is initiated.

Buffer Status Reporting and its Impact on Resource Scheduling

To highlight the problems that may occur in current LTE systems in viewof the above outlined buffer status reporting procedure and relatedscheduling behavior of the eNode Bs, an exemplary scenario is assumed inthe following where there exists at least one radio bearer that carriesdata which is intended to be transmitted on semi-persistently configureduplink resources (semi-persistently scheduled radio bearer). Forsimplicity of the explanations, it is further assumed that this radiobearer is carrying data of a VoIP (Voice over IP) service. The radiobearer is therefore also referred to in the following as a “VoIPbearer”.

Assuming that the VoIP bearer is the only active bearer and new VoIPdata arrives in the UE buffer which was empty previously, the arrival ofthe new VoIP data will trigger a buffer status report (BSR) for theLogical Channel Group (LCG) the logical channel the VoIP bearer isassigned to, as described above, as can be seen in FIG. 7. The bufferstatus report triggers a scheduling request including the buffer statusreport. The scheduling request (SR) is sent to the eNode B on the nextuplink control channel (PUCCH) resource. Once the eNode B is informed onthe buffer status in the user equipment, the eNode B assigns a dynamicuplink radio resource by means of signaling an uplink grant on thedownlink control channel (PDCCH) resources. Four TTIs after reception ofthe grant, the uplink radio resources are available and the VoIP datacan be transmitted to eNode B.

Assuming that there is more than one radio bearer configured and morethan one radio bearer assigned to the Logical Channel Group the VoIPbearer is belonging to, the eNode B only knows that the transmitteduplink data originated from the VoIP bearer after reception of the data.

Since IP packets containing VoIP data will undergo header compression(Robust Header Compression (RoHC)—see Bormann et al., IETF RFC 3095,“RObust Header Compression (ROHC): Framework and four profiles: RTP,UDP, ESP, and uncompressed”, available at http://www.ietf.org) in thePDCP layer, the first few VoIP packets of the VoIP bearer may be assumedlarger than those following afterwards in steady state operation of theheader compression scheme, since the header compression needs to analyzethe first packets in order to determine the compression parametersbefore the compression is activated and before the compression iseffective.

The above description is the reason that in the case of VoIP trafficeNode B needs to wait for a few packets until it can determine thecompressed VoIP data size in order to allocate the correct size forsemi-persistently configured resources.

The above explanations apply e.g. to VoIP data, on the other hand, it isnot excluded that radio bearers carrying data suitable to be transmittedon semi-persistently configured resources that show a stable data sizefrom the beginning of the data transmission are not subject to headercompression.

Once the semi-persistently configured resources in the uplink areactivated and still only one VoIP bearer is actively having data thefollowing scenario can be assumed. VoIP data has a typical periodicityof 20 ms, so the eNode B configures the semi-persistent uplink resourceswith a periodicity of 20 ms. In order to have low latency it isdesirable to have the configured uplink resources available as soon asthe VoIP data is arriving in the UE buffer. However, due to theuncertainty of the data arrival of the VoIP packets in the UE buffer,the eNode B cannot exactly determine the TTI where the configuredresources should start. Therefore data arrival will be in one of theTTIs in between two configured semi-persistently uplink resources. In agood configuration the arrival of VoIP data packets will be just beforethe semi-persistently configured uplink resources become available.

Since the VoIP bearer is the only active radio bearer it can be assumedthat the configured uplink grant is sufficient to empty the buffer ofthe UE. This means that all data in the buffer can be transmitted in thesemi-persistently configured uplink resource and that the next VoIP datapacket will arrive in an empty buffer at UE side. Furthermore, it can beassumed that while the VoIP bearer is the only active bearer, it is notthe only radio bearer that is set up by the UE. Since the VoIP dataarrives in an empty buffer of the UE, a buffer status report istriggered. This buffer status report becomes available in a TTI where nouplink resources are available. According to the standard LTEspecifications this situation triggers a scheduling request to be sentby the UE. The scheduling request is delivered to eNode B at the nextavailable TTI with a configured uplink control channel (PUCCH). Thescenario described so far is exemplarily shown in FIG. 8.

Taking the behavior of the current LTE specification the arrival of datawhich is intended for the semi-persistently scheduled uplink resourcesis creating an unnecessary buffer status report that is delivered to theeNode B. Since the buffer status report only reports the buffer statusper Logical Channel Group, the eNode B might not be aware data of whichradio bearer has triggered the buffer status report. Hence, the eNode Bcannot be sure that the semi-persistently scheduled resource issufficient for delivering the data in the UE buffer in the uplink (e.g.the VoIP packet might have arrived after eNode B received the bufferstatus report). Therefore, the eNode B needs to assign a dynamic uplinkresource to UE by means of a dynamic grant in order to assure speedydata delivery. Since dynamically scheduled uplink resources areallocated 4 transmission time intervals after sending the correspondingdynamic grant on the PDCCH, there are two scenarios for the uplink datadelivery of the VoIP packet:

The dynamically scheduled resources are available before thesemi-persistently scheduled resources: VoIP packet is transmittedaccording to the dynamic grant, so that the semi-persistently scheduledresources are wasted.

The dynamically allocated resources are available after thesemi-persistently scheduled resources: The VoIP packet is transmitted onthe semi-persistently scheduled resources, and the dynamically allocatedresources are wasted.

In both scenarios the dynamic grant is unnecessary and either thedynamic or the semi-persistently scheduled resources are wasted.

In the following the scenario above is extended to a situation wherethere are two active VoIP bearers configured at the UE. It is assumedthat a first VoIP bearer is already active and semi-persistentlyscheduled resources are configured for its data—see FIG. 9.

Every time new data from the first VoIP bearer arrives in the UE abuffer status report and a scheduling request is triggered as describedabove. Once the eNode B receives the buffer status report, it cannotknow from which of the two configured VoIP bearers the data reported onin the buffer status report stems from. Hence, the eNode B needs to givea dynamic grant to the UE in order to assure a speedy and correct datadelivery.

As can be seen in FIG. 9, if data from the second VoIP bearer arrives inthe UE buffer, the buffer is once again empty and a new buffer statusreport and a scheduling request is triggered. Since the eNode B alreadyreceived data of the first radio bearer on the dynamically allocatedresources, it knows that the data reported in the new buffer statusreport must be from the second VoIP bearer. If the eNodeB received thebuffer status well before the next TTI in which the UE has been assignedsemi-persistently allocated resources, the eNode B could override thesemi-persistently allocated resources with a dynamic uplink grant thatfits the size of the data of the second VoIP bearer, which means thatboth the data of the first and the second VoIP bearer can be transmittedon the overwritten semi-persistently allocated uplink resources.However, if the buffer status report arrives too late in the eNode B,the eNode B needs to signal an additional dynamic uplink grant that willallocate dynamically allocated resources in a TTI after the TTI wherethe semi-persistently allocated uplink resources are configured. Thiscan result in unnecessary segmentation and delay to the data of the VoIPbearers.

SUMMARY OF THE INVENTION

One object of the invention is to propose a new buffer status reportingscheme that avoids unnecessary grants from the network. Advantageously,this new buffer status reporting scheme should be operable inconfigurations where one or more semi-persistently scheduled radiobearers are configured for a communication node.

A further object of the invention is to suggest a new handling of theresource usage in systems, where radio resources can be allocatedaccording to different scheduling modes. Advantageously, the newresource usage scheme is co-operating with the new buffer statusreporting scheme.

Another object of the invention is to suggest a new scheduling schemethat is taking advantage of the new buffer status reporting schemeand/or handling of the resource usage.

At least one of these objects is solved by the subject matter of theindependent claims. Advantageous embodiments are subject to thedependent claims.

One aspect of the invention is related to a transmission scheme forbuffer status reports in a mobile communication system. It is assumedthat the scheduler of the radio resources of the mobile communicationsystems can utilize different scheduling modes for allocating radioresource. According to this aspect of the invention, the triggeringand/or generation of the status buffer reports takes into account thescheduling mode of the respective radio bearer's data of which availablefor transmission in a communication node, e.g. a mobile terminal/userequipment. Given that data of a radio bearer is pending for transmissionin a communication node, the decision on whether or not to report on thedata of the radio bearer in the status buffer report is depending on theradio bearer's scheduling mode and the status thereof. If no radiobearer of which data is available for transmission in a buffer of thecommunication node is fulfilling given criteria for inclusion to thebuffer status report, an empty buffer status report may be sent (e.g. incase of a periodic buffer status report).

According to this aspect of the invention, one embodiment thereofprovides a method for transmitting a buffer status report by acommunication node in a mobile communication system. The methodcomprises generating a buffer status report taking into account thescheduling mode of a respective radio bearer and the scheduling modestatus of the respective radio bearer to decide whether data of arespective radio bearer is considered in the buffer status report, andtransmitting the buffer status report, if there is any radio bearer'sdata to be considered in the buffer status report. As explained above,if there is no data of any radio bearer considered to fulfil the givenset of criteria, the buffer status report is “empty” and is not sent.

Furthermore, also the triggering mechanism of buffer status reports assuch (e.g. by some non-periodic event) may consider the scheduling mode.For example, the arrival of new data in a transmission buffer of acommunication node may be triggering a buffer status report only, ifcertain criteria related to the scheduling mode of the radio bearer towhich the data belong are fulfilled. For example, if the data arrivingin the transmission buffer is data of a semi-persistently scheduledradio bearer and an activated semi-persistent resource allocation istaking into account this semi-persistently scheduled radio bearer, nobuffer status report is triggered. In a further example, if a triggerevent is depending on data already present in the transmission bufferupon the arrival of new data in the transmission buffer, already presentdata of semi-persistently scheduled radio bearers considered in thesemi-persistent resource allocation buffer in the transmission shouldnot effect the triggering decision.

In an exemplary embodiment, the scheduling modes available include adynamic scheduling mode in which radio resources are dynamicallyallocated by dynamic grants and a semi-persistent scheduling mode inwhich radio resources are allocated on a semi-persistent basis bysemi-persistently configured scheduling grants. In this connection, itshould be noted that the term semi-persistently scheduled radio bearerrefers to a radio bearer carrying data which is applicable tosemi-persistent scheduling and which are transmitted on the activatedsemi-persistently scheduled resources.

In more detail, in this exemplary embodiment of the invention, theactivation status of the semi-persistent resource allocation isconsidered in the generation of the buffer status report, and if thesemi-persistent resource allocation is activated, it is further takeninto account whether or not respective semi-persistently scheduledbearers are considered in the semi-persistent resource allocation.Hence, in this exemplary embodiment the communication node generatingthe buffer status report also keeps track of the status of therespective semi-persistently scheduled radio bearers with respect towhether or not the current semi-persistent resource allocation is takinginto account data of the respective semi-persistently scheduled radiobearers.

As a result, the buffer status report will not include those radiobearers for which an activated semi-persistent resource allocation isconfigured and data of which are accounted for in the currently validsemi-persistent resource allocation.

Again formulated differently, data of dynamically scheduled radiobearers is always reported in the buffer status reports as well as dataof semi-persistently scheduled radio bearers, which are not taken intoaccount yet in the currently valid semi-persistent resource allocation(e.g. if no data of the radio bearer have been transmitted before, sothat the semi-persistent resource allocation is not yet considering thedata of the radio bearer). If semi-persistent resource allocation isdeactivated the buffer status report will report on data of all radiobearers configured at the communication node.

In one exemplary implementation the following exemplary rules may bedefined to decide whether or not data of a given radio bearer isconsidered in the buffer status report. In one example, the bufferstatus report does report on data of a respective radio bearer only, ifany of the following conditions is not met for the respective radiobearer:

a semi-persistent resource allocation is activated,

the radio bearer is a semi-persistently scheduled radio bearer,

data of the radio bearer have already been transmitted on thesemi-persistently allocated radio resource.

Accordingly, if all rules a), b) and c) are true, the data of the radiobearer is not included to the buffer status report. Furthermore, itshould be noted that rule a) is strictly speaking not a per-radio bearerrule, as semi-persistent resource allocation is commonly eitheractivated or deactivated for all radio bearers.

In a further embodiment, the conditions a) through c) are checked foreach radio bearer of which data is comprised in the transmission bufferto decide whether or not to consider the respective radio bearer in thebuffer status report. In one example, the conditions a) through c) arechecked in the order: a)→b)→c), as the checking of the conditions may beinterrupted for data of a given bearer, as soon as any condition is notaffirmed.

In one further exemplary embodiment of the invention, it is assumed thatthere is a plurality of radio bearers configured, wherein at least oneof the radio bearers is a semi-persistently scheduled radio bearer.Furthermore, it should be noted that buffer status report can forexample be generated in response to the arrival of new data in thetransmission buffer of the communication node or on a periodic basis.

In another embodiment of the invention, the buffer status reports aresent in the uplink by a mobile terminal (user equipment) to a basestation (Node B). In this exemplary embodiment, the mobile terminal maybe informed on which of plurality of radio bearers configured at themobile terminal is/are (a) semi-persistently scheduled radio bearer(s).This may be for example realized during setup of the radio bearer or byassigning the at least one semi-persistently scheduled radio bearer to apredetermined logical channel group. Such predetermined logical channelgroup may for example only include semi-persistently scheduled radiobearers. For example, the buffer status report may indicate the logicalchannel groups to which the radio bearer considered in the buffer statusreport belong, so as to provide the receiving node (typically a Node Bcomprising the scheduler) with some information on which services (radiobearers) have new data available for transmission. This information maybe exploited in a new scheduling mechanism, as will be outlined below infurther detail.

Another aspect of the invention is to suggest a new utilization of theallocated radio resources in a mobile communication system, where radioresources can be allocated by means of different scheduling modes. Inthis respect, a further embodiment of the invention provides a methodfor generating a transport block for transmission on an allocated radioresource. According to this method, data of at least one radio bearer ismultiplexed to a transport block taking into account the scheduling modeof a respective radio bearer and the and scheduling mode status of therespective radio bearer. Furthermore, the multiplexing also takes intoaccount whether the allocated radio resource is a semi-persistentlyallocated radio resource or a dynamically allocated radio resource. Uponhaving generated the transport block, same is transmitted on theallocated radio resource.

In one exemplary implementation, it is checked whether the allocatedradio resource is a semi-persistently allocated radio resource or adynamically allocated radio resource. If the allocated radio resource isa dynamically allocated radio resource, the following data of radiobearers are multiplexed to the transport block, as available fortransmission:

buffer status reports (e.g. respective MAC control elements comprisingthe buffer status reports),

data of dynamically scheduled radio bearers,

data of semi-persistently scheduled radio bearers, if semi-persistentresource allocation has not yet been activated, and

data of semi-persistently scheduled radio bearers not considered in thecurrent semi-persistent resource allocation, if semi-persistent resourceallocation has been activated.

If the allocated radio resource is a semi-persistently allocated radioresource, data of those semi-persistently scheduled radio bearers aremultiplexed to the transport block, as available for transmission, thatare considered in the current semi-persistent resource allocation. Asavailable for transmission means that only data of those radio bearerswhich have data in the transmission buffer may be multiplexed. If nodata of a radio bearer is pending for transmission, no data of this canbe multiplexed to the transport block.

Using the multiplexing rules as defined above, it can be assured thatdata of semi-persistently scheduled radio bearers is always transmittedon the semi-persistently allocated resources, if same are (re-)activatedand if the respective radio bearer has been already considered in theconfigured semi-persistently resource allocation. Otherwise, the data ofsemi-persistently scheduled radio bearers is transmitted via the dynamicresources allocated by dynamic grants.

In a more detailed exemplary implementation according to a furtherembodiment of the invention, if the allocated radio resource is asemi-persistently allocated radio resource, the step of multiplexingmultiplexes data of a semi-persistently scheduled radio bearer to thetransport block, as available for transmission, in case data of thesemi-persistently scheduled radio bearer has not yet been transmitted ona semi-persistently allocated radio resource in a previous transmissiontime interval, and in case a (re-)activation of the semi-persistentresource allocation occurred since transmitting data of thesemi-persistently scheduled radio bearer on a dynamically allocatedradio resource. In this example, it can thus be taken into account inthe multiplexing of the data to a transport block for transmission on asemi-persistently scheduled resource, whether or not the semi-persistentresource allocation presently configured has taken into account the dataof the semi-persistently scheduled radio bearer.

Furthermore, in another more detailed exemplary implementation, theoverwriting of semi-persistently scheduled resources within atransmission time interval (TTI) by dynamic grants may be taken intoaccount. In this exemplary implementation data of all radio bearers ismultiplexed to the transport block, as available for transmission, ifthe allocated radio resource for a given transmission time interval is asemi-persistently allocated radio resource, but a dynamic grant has beenreceived for the transmission time interval, thereby overwriting thesemi-persistent resource allocation within the transmission timeinterval. Hence, in this overwrite situation where the dynamic grantchanges (“overwrites”) the semi-persistent grant, data of all bearersmay be transmitted in the radio resource.

In case there is more data available for transmission in a communicationnode than can be transmitted in the a allocated radio resource, themultiplexing of the radio bearers may for example take into account thepriority of the respective radio bearers to decide on the order in whichdata of the radio bearers is multiplexed to the transport block.

In a further embodiment of the invention, a resource allocation for theallocated radio resource is received, where the resource allocationindicates the transport block size and the modulation and coding schemefor the transmission of the transport block. Accordingly, thecommunication node to transmit the transport block will code thetransport block according to the modulation and coding scheme to obtaincoded data and will modulate the coded data according the modulation andcoding scheme to obtain at least one modulation symbol. The at least onemodulation symbol is then transmitted on the allocated radio resource.

As indicated above, the method for transmitting a buffer status reportaccording to any exemplary embodiment described herein may be readilycombined with the method for generating a transport block fortransmission on an allocated radio resource according to any exemplaryembodiment described herein. By combining the methods, i.e. themultiplexing of data of radio bearers to a transport block depending onthe type of radio resource allocation (dynamic or semi-persistent) incombination with the rules on data of which radio bearers is reported inthe buffer status report provides the receiver of buffer status reportsand transport blocks, commonly a base station (eNode B), with additionalinformation on the status of the transmitter, commonly a mobile terminal(user equipment), which may be for example exploited in an optimizedscheduling, as will be outlined below.

As indicated above, another aspect of the invention is an optimizedscheduling of mobile terminals by a base station, which may be interalia optimized on the (additional) information implicit to the bufferstatus reports from the mobile terminals and their transmissions on theuplink. Accordingly, a further embodiment of the invention is related toa method for scheduling radio resources in a mobile communicationsystem. The scheduler allocates radio resources to mobile terminal on adynamic and semi-persistent basis. The scheduler determines thescheduling mode of radio bearers of which data is comprised in atransport block received from the mobile terminal on a dynamicallyallocated radio resource and reactivates a semi-persistent resourceallocation of the mobile terminal (reactivates means that an alreadyactivated semi-persistent resource allocation is activated again), basedon the scheduling mode of the respective radio bearers of which data iscomprised in a transport block.

In more detail and exemplarily considering the multiplexing behaviour asdiscussed previously herein, if data of a semi-persistently scheduledradio bearer is comprised in the transport block transmitted on adynamically allocated radio resource, this could be taken as anindication that the semi persistent resource allocation for the mobileterminal is not taking into account data of such radio bearer yet.Accordingly, the scheduler may decide to reactivate the semi-persistentresource allocation to account for the data of semi-persistentlyscheduled radio bearer (i.e. to change the semi-persistent configurationof radio resources for semi-persistently scheduled radio bearers).

If considering the exemplary case of a semi-persistently scheduled radiobearer carrying an IP-based service employing IP header compression,such as for example VoIP, it may be advantageous if the reactivation ofthe semi-persistent resource allocation of the mobile terminal isperformed upon the data rate of the data of the semi-persistentlyscheduled radio bearer is in a steady state. In this example, the dataof the semi-persistently scheduled radio bearer may be for exampletransmitted on the dynamically allocated radio resource until the datarate, respectively size of the data packets reaches a steady state.

In a further embodiment of the invention the radio bearers of which datais comprised in a transport block received from the mobile terminal onsemi-persistently scheduled radio resource is monitored a thesemi-persistent resource allocation of the mobile terminal can befurther reactivated or even deactivated based on whether or not arespective semi-persistently scheduled radio bearer configured for themobile terminal is active or not, i.e. whether its service is generatingdata for transmission or not.

A further aspect of the invention is the implementation of the differentmethods described herein in hardware and/or software. Accordingly,another embodiment of the invention relates to a mobile terminal fortransmitting a buffer status report in a mobile communication system.The mobile terminal comprises a processing unit for generating a bufferstatus report taking into account the scheduling mode of a respectiveradio bearer and status of the scheduling mode to decide whether data ofa respective radio bearer is considered in the buffer status report, anda transmitter for transmitting the buffer status report, if there is anyradio bearer's data to be considered in the buffer status report.

Furthermore, in a more specific embodiment of the invention, whendeciding on whether data of the respective radio bearer is considered inthe buffer status report, the processing unit is adapted to take intoaccount:

the activation status of the semi-persistent resource allocation, and

if the semi-persistent resource allocation is activated, whether or nota respective semi-persistently scheduled bearer is considered in thepresently configured semi-persistent resource allocation.

The mobile terminal according to a further embodiment of the inventionfurther comprises means adapted to perform the steps of the method fortransmitting a buffer status report according to any exemplaryembodiment described herein.

A further embodiment of the invention provides another mobile terminalthat is capable of generating a transport block for transmission on anallocated radio resource. This mobile terminal comprises a multiplexerfor multiplexing data of at least one radio bearer to a transport blocktaking into account the scheduling mode of a respective radio bearer andthe and status of the scheduling mode and whether the allocated radioresource is a semi-persistently allocated radio resource or adynamically allocated radio resource, and a transmitter for transmittingthe transport block on the allocated radio resource.

The mobile terminal according to a more specific embodiment of theinvention is further comprising a processing unit for checking whetherthe allocated radio resource is a semi-persistently allocated radioresource or a dynamically allocated radio resource. The mobileterminal's multiplexer is capable of multiplexing to the transport blockthe following data of radio bearers, as available for transmission, ifthe allocated radio resource is a dynamically allocated radio resource:

buffer status reports (e.g. respective MAC control elements comprisingthe buffer status reports),

data of dynamically scheduled radio bearers,

data of semi-persistently scheduled radio bearers, if semi-persistentresource allocation has not yet been activated, and

data of semi-persistently scheduled radio bearers not considered in thecurrent semi-persistent resource allocation, if semi-persistent resourceallocation has been activated.

Furthermore if the allocated radio resource is a semi-persistentlyallocated radio resource, the multiplexer multiplexes data of thosesemi-persistently scheduled radio bearers to the transport block, asavailable for transmission, that are considered in the currentsemi-persistent resource allocation.

In another embodiment of the invention, if the allocated radio resourceis a semi-persistently allocated radio resource, the multiplexer of themobile terminal is multiplexing data of those semi-persistentlyscheduled radio bearers to the transport block, as available fortransmission, data of which has not yet been transmitted on asemi-persistently allocated radio resource previously, in case areactivation of the semi-persistent resource allocation occurred sincetransmitting data of said semi-persistently scheduled radio bearer on adynamically allocated radio resource.

The mobile terminal according to another embodiment of the inventionfurther comprises means to perform the steps of the method forgenerating a transport block for transmission on an allocated radioresource according to any exemplary embodiment described herein.

Another embodiment of the invention is relating to a scheduling node,such as for example a base station (eNode B), for scheduling radioresources in a mobile communication system. The scheduling nodecomprises a resource allocation unit for allocating radio resources tomobile terminal on a dynamic and semi-persistent basis, and a processingunit for determining the scheduling mode of radio bearers of which datais comprised in a transport block received from the mobile terminal on adynamically allocated radio resource. The resource allocation unit iscapable of reactivating a semi-persistent resource allocation of themobile terminal, based on the scheduling mode of the respective radiobearers of which data is comprised in a transport block.

The scheduling node according to a further embodiment of the inventioncomprises means to perform the steps of the method for scheduling radioresources in a mobile communication system as described in one of thevarious embodiments of the invention herein.

Moreover, a further embodiment of the invention is related to a computerreadable medium storing instructions that, when executed by a processorof a mobile terminal, cause the mobile terminal to transmit a bufferstatus report by a communication node in a mobile communication system,by generating a buffer status report taking into account the schedulingmode of a respective radio bearer and status of the scheduling mode todecide whether data of a respective radio bearer is considered in thebuffer status report, and transmitting the buffer status report, ifthere is any radio bearer's data to be considered in the buffer statusreport.

The computer readable medium according another embodiment of theinvention is, further storing instructions that, when executed by theprocessor of the mobile terminal, cause the mobile terminal to performthe steps of the method for transmitting a buffer status reportaccording to any exemplary embodiment described herein.

Another embodiment provides a further computer readable medium storinginstructions that, when executed by a processor of a mobile terminal,cause the mobile terminal to generate a transport block for transmissionon an allocated radio resource, by multiplexing data of at least oneradio bearer to a transport block taking into account the schedulingmode of a respective radio bearer and the and status of the schedulingmode and whether the allocated radio resource is a semi-persistentlyallocated radio resource or a dynamically allocated radio resource, andtransmitting the transport block on the allocated radio resource.

Also this computer readable medium may optionally further storeinstructions that, when executed by the processor of the mobileterminal, cause the mobile terminal to perform the steps of the methodfor generating a transport block for transmission on an allocated radioresource according to any exemplary embodiment of the inventiondescribed herein.

A computer readable medium according to another embodiment of thisinvention is storing instructions that, when executed by a processor ofa scheduling node, cause the scheduling node to schedule radio resourcesin a mobile communication system, by allocating radio resources tomobile terminal on a dynamic and semi-persistent basis, determining thescheduling mode of radio bearers of which data is comprised in atransport block received from the mobile terminal on a dynamicallyallocated radio resource, and reactivating a semi-persistent resourceallocation of the mobile terminal, based on the scheduling mode of therespective radio bearers of which data is comprised in a transportblock.

The computer readable medium may optionally further store instructionsthat, when executed by the processor of the scheduling node, cause thescheduling node to perform the method for scheduling radio resources ina mobile communication system according to one of the exemplaryembodiments outlined herein.

BRIEF DESCRIPTION OF THE FIGURES

In the following the invention is described in more detail in referenceto the attached figures and drawings. Similar or corresponding detailsin the figures are marked with the same reference numerals.

FIG. 1 shows an exemplary network architecture of a SAE/LTEcommunication system, in which the invention may be utilized,

FIG. 2 shows an exemplary SAE Bearer Architecture,

FIGS. 3 and 4 show an exemplary localized allocation and distributedallocation of the uplink bandwidth in a single carrier FDMA scheme,

FIG. 5 shows a flow chart of a procedure for generating a triggeredbuffer status report in a mobile communication system according to oneexemplary embodiment of the invention,

FIG. 6 shows a flow chart of a procedure for multiplexing data to atransport block for transmission on an allocated radio resourceaccording to an exemplary embodiment of the invention,

FIG. 7 shows exemplary triggering and transmission of a buffer statusreport in a 3GPP LTE system,

FIGS. 8 & 9 show exemplary uplink data transmissions and related bufferstatus reporting in an 3GPP LTE system, where unnecessary resourceallocation occurs,

FIG. 10 shows an exemplary transmission of uplink data according to anembodiment of the invention, used for highlighting the advantageouseffects obtained by employing the concepts of the invention,

FIG. 11 shows an exemplary transmission of uplink data according to anembodiment of the invention, used for highlighting the advantageouseffects obtained by employing the concepts of the invention and improvedscheduling, and

FIG. 12 shows the transport block size of a semi-persistent resourceallocation for two semi-persistently scheduled radio bearers accordingto an exemplary embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The following paragraphs will describe various embodiments of theinvention. For exemplary purposes only, most of the embodiments areoutlined in relation to an orthogonal single-carrier uplink radio accessscheme according to the SAE/LTE discussed in the Technical Backgroundsection above. It should be noted that the invention may beadvantageously used for example in connection with a mobilecommunication system such as the SAE/LTE communication system previouslydescribed, but the invention is not limited to its use in thisparticular exemplary communication network.

The explanations given in the Technical Background section above areintended to better understand the mostly SAE/LTE specific exemplaryembodiments described herein and should not be understood as limitingthe invention to the described specific implementations of processes andfunctions in the mobile communication network. Nevertheless, theimprovements proposed herein may be readily applied in thearchitectures/systems described in the Technical Background section andmay in some embodiments of the invention also make use of standard andimproved procedures of theses architectures/systems.

One aspect of the invention is related to a transmission scheme forbuffer status reports in a mobile communication system. It is assumedthat the scheduler of the radio resources of the mobile communicationsystems can utilize different scheduling modes for allocating radioresource. According to this aspect of the invention, the triggeringevents for buffer status reports as well as the generation of the bufferstatus reports takes into account the scheduling mode, e.g. dynamic orsemi-persistent scheduling, of the respective radio bearer data of whichis available for transmission in a communication node, e.g. mobileterminal/user equipment. Furthermore, the scheduling mode status, e.g.the activation/deactivation of the semi-persistent scheduling, may befurther taken into account when deciding on which data of radio bearersis reported in the buffer status report.

In one example, the available scheduling modes for the radio bearersinclude a dynamic scheduling mode in which radio resources aredynamically allocated by dynamic grants and a semi-persistent schedulingmode in which radio resources are allocated on a semi-persistent basisby semi-persistently configured scheduling grants. In this connection,it should be noted that the term semi-persistently scheduled radiobearer refers to a radio bearer carrying data which is applicable tosemi-persistent scheduling and which are transmitted on the activatedsemi-persistently scheduled resources. Whether or not a semi-persistentresource allocation is utilized by the scheduler for radio bearerscarrying data suitable for semi-persistent scheduling is up to thescheduler's decision—of course the scheduler will try to allocate radiobearers carrying data suitable for semi-persistent scheduling on asemi-persistent resource allocation, but this is not mandatory and maybe influenced by other scheduling parameters, like channel quality,load, etc.

In line with this example, in one embodiment of the invention, theactivation status of the semi-persistent resource allocation isconsidered in the triggering and generation of the buffer status report,and if the semi-persistent resource allocation is activated, it isfurther taken into account whether or not respective semi-persistentlyscheduled bearers are considered in the semi-persistent resourceallocation. Hence, in this exemplary embodiment the communication nodeto transmit buffer status reports also keeps track of the status of therespective semi-persistently scheduled radio bearers with respect towhether or not the current semi-persistent resource allocation is takinginto account data of the respective semi-persistently scheduled radiobearers.

Concerning the triggering of buffer status reports, it is proposed thatthe arrival of new data in a transmission buffer of a communication nodeis triggering a buffer status report only if certain criteria related tothe scheduling mode of the radio bearer to which the data belong. Forexample, if the data is data of a semi-persistently scheduled radiobearer and an activated semi-persistent resource allocation is takinginto account this semi-persistently scheduled radio bearer, no bufferstatus report is triggered.

It is further proposed that a triggered buffer status report will notinclude those radio bearers for which an activated semi-persistentresource allocation is configured and data of which are accounted for inthe currently valid semi-persistent resource allocation. In other terms,data of dynamically scheduled radio bearers is always reported in thebuffer status reports as well as data of semi-persistently scheduledradio bearers, which are not taken into account yet in the currentlyvalid semi-persistent resource allocation (e.g. if no data of the radiobearer have been transmitted before, so that the semi-persistentresource allocation is not yet considering the data of the radiobearer). If semi-persistent resource allocation is deactivated thebuffer status report will report on data of all radio bearers configuredat the communication node.

Another aspect of the invention is the definition of new multiplexingrules for filling a transport block to be transmitted on an allocatedradio resource. Essentially in line with the differentiation of radiobearers based on their scheduling mode and scheduling mode status, alsonew multiplexing rules can be introduced. The multiplexing rulesconsider first of all the type of resource allocation. Hence, for eachradio resource within a given transmission time interval (TTI), it isconsidered in the multiplexing of data to a transport block to betransmitted in the given transmission time interval, whether theresource allocation pertaining to this transmission time interval is adynamic resource allocation (dynamic grant) or is a semi-persistentresource allocation (semi-persistent grant).

If the resource allocation is a semi-persistent resource allocation(which implies that semi-persistent resource allocation is activated),it is ensured that only data of semi-persistently scheduled radiobearers having been considered in the semi-persistent resourceallocation is multiplexed to the transport block of the giventransmission time interval.

Having been considered means in this context that it is implicit to thesemi-persistent resource allocation and its activation that therespective radio bearer has been considered in the semi-persistentresource allocation. For example, as will be outlined below, data ofsemi-persistent radio bearers transmitting data for the first time aretransmitted on dynamic resources first, until the semi-persistentresource allocation is set up or updated, i.e. a new semi-persistentgrant is sent (e.g. yielding a larger transport block size as before toaccount for the radio bearer's data). Upon reception of such asemi-persistent grant adjusting the semi-persistent resource allocation,the data transmitter (e.g. mobile terminal/user equipment) can confirmbased on the indicated transport block size that the radio bearer hasbeen taken into account by the scheduler in the semi-persistent resourceallocation.

Returning to the multiplexing rules, if the resource allocation is asemi-persistent resource allocation (i.e. the resource allocation isdynamic), data of radio bearers not suited for semi-persistentscheduling (i.e. dynamically scheduled radio bearers) and data ofsemi-persistently radio bearers not considered in the semi-persistentresource allocation are multiplexed to the transport block fortransmission in the given transmission time interval. Semi-persistentlyradio bearers not yet considered in the semi-persistent resourceallocation are for example data of radio bearers that for which have notyet provided data previously, so that the scheduler is not yet aware ofthe radio bearer sending data and consequently the radio bearer is notyet considered in the resource allocation of the currently validsemi-persistent grant.

Furthermore, it should be noted that in case semi-persistent resourceallocation is not activated, data of all radio bearers is transmitted onthe dynamically allocated resources. In addition, it should also benoted that in all cases the transport block may be filled with dataaccording to the logical channel priorities of the logical channels towhich the respective radio bearers are mapped. If properly configured,the transport block size of the semi-persistent resource allocationshould be such that all data of semi-persistently scheduled radiobearers (considered in the semi-persistent grant) becoming available fortransmission in between two transmission time intervals in whichsemi-persistent resources are allocated can be transmitted in the giventransmission time interval.

As already briefly indicated above, another aspect of the invention isrelated to exploiting the additional information gained by the datareceiver from the above outlined rules for sending buffer status reportsand filling transport blocks. For example considering that the bufferstatus reports will only report on data of radio bearers requiring adynamic grant, there is no longer any ambiguity with respect to thequestion whether or not the buffer status report has been triggered bydata of a semi-persistently scheduled radio bearer which is alreadyconsidered in the currently activated and configured semi-persistentresource allocation. Accordingly, unnecessary resource allocations canbe avoided in scenarios discussed in the Technical Background section ofthis document. Furthermore, by monitoring data of which bearers istransmitted on the dynamically allocated radio resources, the datareceiver (e.g. base station/eNode B) which is including the scheduler inthis example can also detect semi-persistently scheduled radio bearersbecoming active (i.e. producing data). If data of a semi-persistentlyscheduled radio bearer is detected in a transport block sent on adynamically allocated radio resource, the data receiver (scheduler) canassume that this radio bearer has not yet been accounted for yet in thesemi-persistent resource allocation and could activate thesemi-persistent resource allocation with an updated semi-persistentgrant to account for the additional data of the now activesemi-persistently scheduled radio bearer.

Similarly, when monitoring the transport blocks on the semi-persistentlyallocated radio resources, the data receiver (scheduler) can detectwhich semi-persistently scheduled radio bearers are active and senddata. If it is detected that a service of a semi-persistently scheduledradio bearer becomes inactive (e.g. no data of the semi-persistentlyscheduled radio bearer is sent for a given threshold number oftransmission time intervals in which semi-persistently allocated radioresources are configured), the data receiver (scheduler) could decide tochange (in this case reduce) the semi-persistent grant (in this casereduce the transport block size) to account for a radio bearer becominginactive.

In a more specific implementation according to one exemplary embodimentof the invention, one or more of the semi-persistently scheduled radiobearers convey IP packets of a service and employ IP header compression,as for example suggested in IETF RFC 3095, to compress the IP headers.Furthermore, it may be assumed that this at least one semi-persistentlyscheduled radio bearer periodically generates IP packets relativelyconstant in size, so that after header compression is in a steady statea relatively constant bit rate stream is produced. One example for suchservice would be VoIP, as mentioned before. In this case the size of theIP packets transported via the radio bearer may be varying until IPheader compression reaches its steady state and produces “quasi-static”packet sizes. In order to optimize resource allocation for such type ofservices, the data receiver (scheduler), e.g. in the base station/eNodeB, may therefore await the data of a radio bearer conveying such type ofservice (i.e. the IP packets to which header compression has beenapplied) to reach a steady state before considering same in asemi-persistent resource allocation.

For example, if the base station/eNode B (scheduler) detects data ofsemi-persistently scheduled radio bearer conveying a VoIP service beingtransmitted by a mobile terminal/user equipment on dynamically allocatedresources, the base station/eNode B (scheduler) may not immediatelyupdate the semi-persistent resource allocation, but may await the datato reach a steady state, e.g. when the data of the radio bearer have aquasi-static data rate before updating the semi-persistent resourceallocation.

All aspects of the invention described above are based on adifferentiation of the radio bearer with respect to their schedulingmode being possible in the data transmitter and data receiver, e.g. themobile terminal/user equipment and base station/eNode B, respectively,for uplink data transmissions. In one embodiment of the invention, thedata transmitter is informed by the data receiver on the scheduling modeof the respective radio bearers established between the data transmitterand data receiver. For example, if considering an uplink scenario, thebase station/eNode B could indicate the scheduling mode in a signalingmessage exchanged with the mobile terminal/user equipment during radiobearer setup. In a 3GPP system and assuming that there are twoscheduling modes available, dynamic resource allocation andsemi-persistent resource allocation, this could be accomplished byadding an additional information element (IE)—one flag would besufficient in this case—to the radio bearer setup message of the RRCprotocol that indicates whether the respective radio bearer to which theradio bearer setup message pertains is carrying data which may bescheduled by the base station/eNode B using semi-persistent resourceallocation.

Another option may be to designate one of the available logical channelgroups (LCGs) to which the radio bearers are assigned as a logicalchannel group to which only semi-persistent scheduled radio bearers areassigned. Accordingly, by indicating a radio bearer to be assigned tothis predetermined logical channel group during radio bearer setup, themobile terminal/user equipment is implicitly informed on the radiobearer being potentially scheduled by using semi-persistent resourceallocation.

Regarding the triggering of a buffer status report, in one exemplaryembodiment of the invention, the arrival of new data ofsemi-persistently scheduled radio bearers in the transmission buffer ofa communication node (e.g. mobile terminal/user equipment) that areconsidered in an activated semi-persistent resource allocation are nottriggering a buffer status report. Accordingly, once data becomesavailable on radio bearer and arrives in an empty transmission buffer ofthe communication node, the communication node will first check thefollowing conditions:

Is semi-persistent resource allocation activated?

Is the radio bearer of which data arrived in the transmission buffer asemi-persistently scheduled radio bearer?

Has data of the radio bearer of which new data arrived in thetransmission buffer already been transmitted on the semi-persistentlyallocated radio resource?

If the above conditions are all true, the buffered data of the radiobearer is not considered for buffer status reporting. If one of theconditions above is not met for the data of the radio bearer arriving inthe transmission buffer, a buffer status report is triggered.

Furthermore, it should be noted that also other triggering eventsdefined in the system may need to be adapted. Generally, the triggeringevents depending on the arrival of data in a transmission buffer shouldnot consider (data of) semi-persistent scheduled radio bearers beingconsidered in an active semi-persistent resource allocation.

For example, consider a trigger event according to which data of alogical channel/radio bearer in the transmission buffer trigger a bufferstatus report, if there is only data of radio bearers having a lowerlogical channel priority in the transmission buffer. In this example,there will be no buffer status report, if higher priority data of asemi-persistent scheduled radio bearers being considered in an activesemi-persistent resource allocation (which did not trigger a bufferstatus report) is already present in the transmission buffer.Accordingly, this trigger event should be improved such that data of alogical channel/radio bearer in the transmission buffer trigger a bufferstatus report, if there is only data of dynamically scheduled radiobearers and semi-persistently scheduled radio bearers not considered inan active semi-persistent resource allocation in the transmission bufferhaving a lower logical channel priority.

In one exemplary embodiment of the invention, the trigger events for abuffer status report in a 3GPP LTE system can be redefined as follows. Abuffer status report is thus triggered if (note that the terms logicalchannel and radio bearer can be considered synonyms in these events, asit is assumed that data of a radio bearer is mapped to one logicalchannel, so that there is a one-to-one mapping between logical channelsand radio bearers):

Uplink data, for a logical channel not being considered in a currentlyvalid semi-persistent grant and which belongs to a Logical Channel Group(LCG), becomes available for transmission in the RLC (Radio LinkControl) or PDCP (Packet Data Convergence Protocol). Furthermore, thedata belongs to a logical channel with higher priority than thepriorities of the logical channels for which data is already availablefor transmission and which are not considered in a currently validsemi-persistent grant. A “Regular BSR” is triggered in this case.

Uplink resources are allocated and the number of padding bits in thetransport block (MAC PDU) is equal to or larger than the size of theBuffer Status Report MAC control element. A “Padding BSR” is triggeredin this case.

A serving cell change occurs. A “Regular BSR” is triggered in this case.

Furthermore, a (periodic) buffer status report is also triggered by theexpiry of the following timers:

when the RETX_BSR_TIMER expires and the UE has data available fortransmission a “Regular BSR” is triggered.

when PERIODIC_BSR_TIMER expires, a “Periodic BSR” is triggered.

If there is a buffer status report triggered by any event, thecommunication node will check whether there are any uplink resourcesavailable for the transmission of the buffer status report. If not, thecommunication node sends a scheduling request to be allocated an uplinkresource on which the buffer status report can be sent. Considering forexample, where the mobile terminal/user equipment is to send a bufferstatus report, and there are no PUSCH resources allocated to the mobileterminal/user equipment, the mobile terminal/user equipment transmits ascheduling request to the base station/eNode B to request the dynamicallocation of a PUSCH resource.

In one exemplary embodiment of the invention, buffer status reports maynot be sent on radio resources that have been allocated on asemi-persistent basis, but the communication node that is to transmitthe buffer status report will use only dynamically allocated radioresources for sending the buffer status report. Alternatively, inanother embodiment of the invention, buffer status report may betransmitted on semi-persistently scheduled radio resources as well as ondynamically allocated radio resources

Next, an exemplary embodiment of the invention related to the generationof buffer status reports will be described with respect to FIG. 5.Generally, a buffer status report reports on the data within thetransmission buffer obeying the rules on data of which radio bearers isto be considered as outlined herein. In one exemplary embodiment, thesize of the data in the transmission buffer is reported on a per-logicalchannel group basis. Hence, the data size reported for a particularlogical channel group considered the data of the radio bearers belongingto the respective logical channel group and which are to be consideredaccording to the rules defined herein.

The buffer status report may for example report on one or moreindividual (not all) logical channel groups (short or truncated BSR). Inthis case the a report for a logical channel group within the bufferstatus report consists of field for indicating the a logical channelgroup reported (logical channel group identifier—LCG ID) and a field forindicating the size of the data in the transmission buffer for thoseradio bearers belonging to the logical channel group and to beconsidered in the buffer status reporting. If all logical channel groupsare reported (long BSR), no logical channel group identifiers need to beincluded to the buffer status report but the report may contain only thesize of the data in the transmission buffer for those radio bearersbelonging to the logical channel group and to be considered in thebuffer status reporting for each logical channel group. The bufferstatus report can be for example sent as a MAC control element.

FIG. 5 shows a flow chart of a procedure for generating and (optionally)transmitting a buffer status report in a mobile communication systemaccording to one exemplary embodiment of the invention. The procedureshown in FIG. 5 may be for example performed by a mobile terminal/userequipment if considering uplink data transmissions.

In FIG. 5 it is assumed that some event, like the arrival of new higherpriority data in a transmission buffer of a mobile terminal/userequipment or expiry of a timer for triggering periodic buffer statusreports, has triggered the generation of a buffer status report. Forexemplary purposes, the communication node to send the buffer statusreport on the uplink data in its transmission buffer is a mobileterminal/user equipment and it is further assumed that there are twoscheduling modes for scheduling uplink resources, a dynamic schedulingmode in which radio resources are dynamically allocated by dynamicgrants and a semi-persistent scheduling mode in which radio resourcesare allocated on a semi-persistent basis by semi-persistently configuredscheduling grants.

In this example, it is exemplarily assumed that a full buffer statusreport on radio bearers of all logical channel groups is to be sent. Thefollowing procedure may also be applied to situations where a bufferreport for only one (or not all) logical channel group(s) should besent—in this case, only radio bearers of the respective logical channelgroup(s) need to be evaluated by the following procedure.

For generating the buffer status report, the mobile terminal/userequipment checks 501 whether semi-persistent resource allocation isactivated or not. If this is not the case, the mobile terminal/userequipment adds 502 data of any radio bearer having data in thetransmission buffer to the buffer status report. If the buffer statusreport is intended to be limited to report on one or more logicalchannel group, the only data of those radio bearers belonging to thedesired logical channel group(s) are added to the buffer status report.Subsequently, the buffer status report can be transmitted 507 on thenext uplink resource allocated to the mobile terminal/user equipment.The buffer status is transmitted via the PUSCH, whereby the bufferstatus report is multiplexed to the transport block with other uplinkdata.

If semi-persistent resource allocation is activated, the mobileterminal/user equipment will consider for each radio bearer having datain the transmission buffer whether to report on its data in thetransmission buffer as follows. The mobile terminal/user equipmentselects 503 a radio bearer #i from the radio bearer having data in thetransmission buffer and checks 503 whether this radio bearer #i is asemi-persistently scheduled radio bearer. If this is not the case, i.e.radio bearer #i is a dynamically scheduled radio bearer, the mobileterminal/user equipment considers 504 radio bearer #i in its reporting,e.g. the data of radio bearer #i in the transmission buffer isconsidered for the logical channel group to which radio bearer #ibelongs.

Otherwise, if radio bearer #i is a semi-persistently scheduled radiobearer, the mobile terminal/user equipment next checks 505 whether radiobearer #i is already considered in the currently valid semi-persistentresource allocation. This may be for example accomplished by keeping aflag for each semi-persistently scheduled radio bearer indicating thiscircumstance. The flag may be for example set to indicate the radiobearer #i being considered in the currently valid semi-persistentresource allocation, if a new activation (also herein referred to as“reactivation”) of the semi-persistent resource allocation has occurred(i.e. a new semi-persistent grant has been received) after having sentdata of a radio bearer on dynamically allocated resources.

If radio bearer #i is not considered in the currently validsemi-persistent resource allocation, e.g. the corresponding flag is notset, radio bearer #i considered 504 in the buffer status report as thedynamically scheduled radio bearers. Otherwise, when radio bearer #i isalready considered in the currently valid semi-persistent resourceallocation, no reporting on its data in the transmission buffer is done,since the mobile terminal/user equipment can assume that the currentlyvalid and active semi-persistent resource allocation already allocatessufficient resources for transmitting data of radio bearer #i.

If there is 506 at least one further radio bearer having data in thetransmission buffer, the procedure returns to step 503, where the nextradio bearer is selected. Effectively, steps 503 and 505 (and step 504as applicable) are repeated for all radio bearers having data in thetransmission buffer of the mobile terminal/user equipment. The order inwhich the individual radio bearers having data in the transmissionbuffer are processed may be for example based on the logical channelgroups they belong to. For example, if the buffer status report isreporting on a logical channel group basis, it may be advantageous toprocess the radio bearers of one logical channel group one after anotheras defined above and to sum the size of their data in the transmissionbuffer (for those radio bearers to be considered in the reporting) toreport one single data size per logical channel group.

In this connection, it should be noted that in case the mobileterminal/user equipment has only (one or more) radio bearers configuredthat are all considered and transmitted on an activated semi-persistentresource allocation, periodic buffer status reports will indicate nodata in the mobile terminal's/user equipment's transmission buffer beingpending for uplink transmission.

Next, another aspect of the invention, the utilization of the grantedradio resources and more specifically new multiplexing rules fortransmitting the data of radio bearers that can be scheduled accordingto different scheduling modes will be discussed in further detail. Onefeature of this aspect of the invention is that there is adifferentiation of allocated uplink resources based on the allocationtype, i.e. the respective scheduling mode. Furthermore, the utilizationof the allocated radio resources may also take into account thescheduling mode of the different radio bearers having data pending fortransmission.

For exemplary purposes, this feature will be outlined assuming thatradio resources can be scheduled dynamically or on a semi-persistentbasis as discussed previously herein. Every time new data of a radiobearer arrives in the transmission buffer which is of higher prioritythan the data already available in the transmission buffer of thetransmitting communication node (e.g. a mobile terminal/user equipment)upon a transmission opportunity in the uplink occurring (i.e. there is atransmission time interval where the communication node is allocatedradio resources), the communication node performs further checks todetermine which data pending in the transmission buffer will betransmitted. First of all, the communication node checks 601, whetherthe resource allocated within the transmission time interval has beenallocated by a dynamic grant (i.e. is dynamically allocated) or has beenallocated by a semi-persistent grant (i.e. by a semi-persistent resourceallocation). Please note that in case there is resource in the giventransmission time interval that has been allocated by a semi-persistentgrant, this also implies that semi-persistent resource allocation hasbeen activated.

If the radio resource is a semi-persistently scheduled resource, thecommunication node only transmits data of radio bearers that aresuitable for semi-persistent scheduling and are considered in thecurrently valid and activated semi-persistent grant. In this exemplaryembodiment of the invention, this is realized by the communication nodefirst selects 602 a semi-persistently scheduled (SPS) radio bearer #ihaving data in the transmission buffer (e.g. the SPS radio bearer couldbe selected according to their logical channel priority) and checks 603,whether SPS radio bearer #i is considered in the currently validsemi-persistent grant (SPS resource allocation). If this should be thecase, the data of SPS radio bearer #i is added 604 (multiplexed) to thetransport block.

If SPS radio bearer #i is not considered in the currently validsemi-persistent grant or after the data of SPS radio bearer #i havingbeen added to the transport block, the communication node determines605, whether the there is a further semi-persistently scheduled radiobearer having data in the transmission buffer. If so, the communicationnode jumps back to step 602 and selects the next semi-persistentlyscheduled radio bearer having data in the transmission buffer (e.g.again based on the logical channel priority) and processes this nextsemi-persistently scheduled radio bearer as described above. Upon havingfilled the transport block, same is transmitted 606 on the allocatedsemi-persistently allocated resource.

If it is determined in step 601 that the allocated radio resource in thetransmission time interval is dynamically allocated by a dynamic grant,it is next checked 607 whether any buffer status report is pending fortransmission. If so, the buffer status report is added 608 to thetransport block. In one exemplary implementation, the transport block iscorresponding to a PDU (Protocol Data Unit) of the MAC entity (MediumAccess Control entity) and the buffer status report is comprised to theMAC PDU's header as a BSR control element.

If there is no buffer status to be reported or after having added 608the buffer status report to the transport block, it is next iteratedthrough the radio bearers having data in the transmission buffer anddata of dynamically scheduled radio bearers is added to the transportblock. Furthermore, if semi-persistent resource allocation is activated,also data of semi-persistently scheduled radio bearers not considered inthe activated semi-persistent resource allocation is added to thetransport block. If semi-persistent resource allocation is deactivated,data of all semi-persistently scheduled radio bearers is added to thetransport block as available in the transmission buffer (in thisexample, semi-persistent resource allocation being deactivated isequivalent to no radio bearer being considered in the semi-persistentresource allocation).

One possible exemplary implementation of this procedure may be realizedas follows. The communication node selects 609 a radio bearer #i fromthe radio bearers having data in the transmission buffer and checks 610next, whether radio bearer #i is dynamically scheduled orsemi-persistently scheduled. If radio bearer #i is not asemi-persistently scheduled radio bearer, the data of radio bearer #i isadded 612 to the transport block. If radio bearer #i is asemi-persistently scheduled radio bearer, it is further determined 611,whether radio bearer #i is considered in the current semi-persistentresource allocation or not. In this respect it should be noted that thisdetermination yields “no” for all semi-persistently scheduled radiobearers, if semi-persistently scheduling is deactivated (In this contextit should be noted that a semi-persistently resource allocation may beconfigured (e.g. the periodicity of the allocation), but the configuredresources are not yet known since semi-persistently scheduling is notactivated (i.e. no semi-persistent grant has been sent yet to active thesemi-persistent resource allocation). Hence, the configuration and(de-)activation of semi-persistent scheduling is independent). Ifsemi-persistently scheduling is activated this determination yields“yes” for those semi-persistently scheduled radio bearers that areconsidered in the current semi-persistent resource allocation(respectively currently valid semi-persistent grant).

If the determination in step 611 yields “yes” (which also yieldssemi-persistent scheduling being activated), data of respective radiobearer #i within the transmission buffer is not included to thetransport block. If the determination in step 611 yields “no” data ofrespective radio bearer #i within the transmission buffer is included612 to the transport block.

Step 613 assures that all radio bearers having data in the transmissionbuffer are checked and processed according to the rules outlined above.If all radio bearers having data in the transmission buffer have beenprocessed, the transport block can be sent 606 on the allocated dynamicresource.

The multiplexing behavior for filling the transport block to betransmitted may be summarized as follows:

If the allocated radio resource is a dynamically allocated radioresource the following data can be multiplexed to the transport block:

MAC control elements, including buffer status reports, as available fortransmission,

data of dynamically scheduled radio bearers,

if semi-persistent resource allocation has not yet been activated, dataof all semi-persistently scheduled radio bearers, and

if semi-persistent resource allocation has been activated, data ofsemi-persistently scheduled radio bearers not considered in the currentsemi-persistently resource allocation (respectively semi-persistentgrant),

are multiplexed to a transport block, as available. If the allocatedradio resource is a semi-persistently allocated radio resource, themultiplexer of the communication node multiplexes data of thosesemi-persistently scheduled radio bearers to the transport block whichare already considered in the currently valid semi-persistent resourceallocation (alternatively: the multiplexer of the communication nodemultiplexes data of those semi-persistently scheduled radio bearers tothe transport block data of which have previously been transmitted via asemi-persistently allocated radio resource in a previous transmissiontime interval).

Furthermore, it should be noted that in the exemplary embodiment of theinvention discussed with respect to FIG. 6 above, buffer status reportsare transmitted only on dynamically allocated resources.

Generally, it should be noted that the transport block size of aresource allocation is limited. In a well implemented semi-persistentresource allocation, the transport block size is chosen by the schedulersuch that the data of all semi-persistently scheduled radio bearersconsidered in the semi-persistent resource allocation fits into thetransport block. If for whatever reason some data of a semi-persistentlyscheduled radio bearer considered in the semi-persistent resourceallocation should not fit into the (remaining bits of) the transportblock, segmentation of the data can be used to fill the remaining bitsof) the transport block with at least a part of the data of thesemi-persistently scheduled radio bearer pending in the transmissionbuffer.

Although harder to accomplish, also the dynamic resource allocationshould be implemented ideally such that the communication node cantransmit data of all radio bearers pending for transmission (accordingto the multiplexing rules above) within a single transport block. Asthis is somewhat more difficult to accomplish in view of the lessregular data size of services not suitable for semi-persistent resourceallocation (given that the scheduler does also not want to constantlyallocate transport block sizes extending the data size available fortransmission by far), segmentation of individual data packets from aradio bearer may occur more frequently for dynamic resource allocations.

The above rules for multiplexing the data of different configured radiobearers to a transport block may be alternatively formulated as follows.In another exemplary embodiment the following determinations and stepsare performed (for uplink transmissions):

If data is not from a semi-persistently scheduled radio bearer: Thisdata may only be included in a transport block that is transmittedduring a TTI with dynamic uplink resources

If data is from a semi-persistently scheduled radio bearer:

If semi-persistently scheduling has not been activated: This data may beincluded in a transport block that is transmitted during a TTI withdynamic uplink resources.

If semi-persistently scheduling has been activated:

If the activation/reactivation of the semi-persistently scheduledresources happened after data became available on the semi-persistentlyscheduled radio bearer: This data may only be included in a transportblock that is transmitted during a TTI where semi-persistent uplinkresources are configured. The data is not allowed to be included in atransport block that is transmitted during a TTI with dynamic uplinkresources.

If there was no reactivation of semi-persistently scheduling yet, eventhough data became available on the semi-persistently scheduled radiobearer: If semi-persistently scheduling is already activated, the datamay not be included in a transport block that is transmitted during aTTI where semi-persistent uplink resources are configured. However, thedata may be included in a transport block that is transmitted during aTTI with dynamic uplink resources.

Next, an exemplary embodiment of the invention will be described withrespect to FIG. 10. FIG. 10 is showing an exemplary transmission of data(and buffer status reports) according to the improved procedures fortriggering and transmitting buffer status reports and for multiplexingdata on allocated resources described herein. For exemplary purposes itis referred to uplink data transmission by a user equipment to a eNode B(comprising the scheduling entity) within an improved 3GPP LTE mobilecommunication system. In this example, it is assumed that the userequipment (UE) has set up two VoIP services so that twosemi-persistently scheduled radio bearers (“VoIP bearers”) areconfigured in the user equipment. These two VoIP bearers are referred toas the “1^(st) RB” and the “2^(nd) RB” within FIG. 10. Furthermore,there is also a dynamic scheduled service running in the user equipment,which is conveyed via a dynamically scheduled radio bearer (referred toas “3^(rd) RB” in FIG. 10).

The scheduler (i.e. the eNode B in this example), configuressemi-persistent scheduling via RRC signaling. The user equipment isprovided with a semi-persistent grant (PDCCH (SPS)) that is periodicallyallocating an uplink radio resource on the PUSCH to the user equipment.For a VoIP service, the periodicity of the resource allocation istypically 20 ms as this is the time interval in which the VoIP codec isproducing IP packets containing speech data. It may be assumed thatsemi-persistent resource allocation is activated and thesemi-persistently scheduled uplink radio resources on the PUSCH arematching the data rate of the IP packets produced by the VoIP codecwhich are conveyed by one of the VoIP bearers (here: 1^(st) RB). Inaccordance with the multiplexing rules defined above, all data producedby the VoIP bearer “1^(st) RB” of FIG. 10 are thus transmitted via thesemi-persistently scheduled uplink radio resources.

At some point in time, new data of the VoIP bearer “1^(st) RB” arrive inan empty transmission buffer of the user equipment. In a conventionalimplementation, this event would trigger a buffer status report. Inaccordance with the rules outlined with respect to FIG. 6 above, thearrival of new data of a semi-persistently radio bearer that isconsidered in the activated semi-persistent resource allocation, as itis the case for VoIP bearer “1^(st) RB”, will not trigger a bufferstatus report. Accordingly, no scheduling request and no buffer statusreport is sent by the user equipment in response to the arrival of newdata of VoIP bearer “1^(st) RB” in the transmission buffer.

Some time slots later, data of the dynamically scheduled radio bearer“3^(rd) RB” is arriving in the transmission buffer. The arrival of thisnew data is triggering the transmission of a buffer status report. Inthis embodiment of the invention, it is assumed for exemplary purposedthat buffer status reports are sent via dynamically scheduled resources.Accordingly, the user equipment sends a scheduling request within thenext time slot where a PUCCH is configured (PUCCH (SR)) and receives inresponse thereto from the eNode B a dynamic grant via the PDCCH (PDCCH(DG)) indicating some time slot (or transmission time interval) which isallocated to the user equipment and the transport format (implicitlyindicating the transport block size) for the transmission in this timeslot (or transmission time interval).

The buffer status report of the user equipment is reporting the bufferstatus at the time instance of generating same, i.e. when generating thebuffer status report, there is data of VoIP bearer “1^(st) RB” anddynamically scheduled radio bearer “3^(rd) RB” in the transmissionbuffer. As described above with respect to FIG. 5, the user equipmentonly reports on the data of the dynamically scheduled radio bearer“3^(rd) RB” within the buffer status report, as semi-persistentscheduling is activated (see step 501 of FIG. 5) and the VoIP bearer“1^(st) RB” is considered in the current semi-persistent resourceallocation (see step 505 in FIG. 5). Accordingly, the dynamic grant(PDCCH (DG)) obtained from eNode B in response to the scheduling request(PUCCH (SR)) is used to transmit only the triggered buffer status reporton data of the dynamically scheduled radio bearer “3^(rd) RB”multiplexed with data of the dynamically scheduled radio bearer “3^(rd)RB” (BSR & data (3^(rd) RB)) on the allocated dynamic resource as perthe procedure outlined with respect to FIG. 6 above.

Next, there is new data of VoIP bearer “2^(nd) RB” arriving in thetransmission buffer of the user equipment. VoIP bearer “2^(nd) RB” isassumed not to be considered in the semi-persistent resource allocationcurrently configured for the user equipment, so that—according to therules set out previously—its data needs to be transmitted via adynamically allocated resource. To be allocated such resource, the userequipment used the next transmission time interval where a PUCCH isconfigured to send a scheduling request (PUCCH(SR)) to the eNode B,which allocates dynamic resources and returns a corresponding dynamicgrant (PDCCH(DG)) to the user equipment.

Following the transmission time interval the user equipment sends ascheduling request (PUCCH(SR)) to the eNode B for the data of VoIPbearer “2^(nd) RB”, the user equipment has a semi-persistently scheduledresource allocated. Following the procedure outlined above with respectto FIG. 6, the user equipment will multiplex only data of VoIP bearer“1^(st) RB” in the transmission buffer to this uplink resource (VoIPdata (1^(st) RB)).

Prior to the dynamically allocated PUSCH resource (the allocation ofwhich has been triggered by the scheduling request sent in response tonew data of VoIP bearer “2^(nd) RB” arriving in the transmissionbuffer), new data of dynamically scheduled radio bearer “3^(rd) RB” inthe transmission buffer. As the multiplexing of data to the transportblock for transmission on the dynamically allocated PUSCH resourceconsiders all data present in the transmission buffer upon thegeneration of the transport block, in accordance with the procedure ofFIG. 6, data of dynamically scheduled radio bearer “3^(rd) RB” and dataof VoIP bearer “2^(nd) RB” will be multiplexed to the transport block,e.g. according to the logical channel priorities of the logical channelto which the dynamically scheduled radio bearer “3^(rd) RB” and the VoIPbearer “2^(nd) RB” are mapped, respectively. Depending on the allocationsize, the data of a radio bearer may also be segmented.

Accordingly, in the example outlined with respect to FIG. 10, allallocated resources are used for data transmission so that overall theresource utilization in the uplink is optimized.

A further embodiment of the invention is related to situations, wheremore than one semi-persistently scheduled radio bearer (e.g. two or moreradio bearers for VoIP) are configured and where one of thesemi-persistently scheduled radio bearers which has been inactive forsome time (and is therefore not considered in the semi-persistentresource allocation) is becoming active again or for the first time. Incase semi persistent scheduling is already activated and one or moresemi-persistently scheduled radio bearers are actively transmitting dataon the configured semi-persistent uplink resources, a semi-persistentlyscheduled radio bearer getting active (again)—i.e. generating data—isnot transmitted on the configured semi-persistently allocated uplinkresources until a (re-)activation of semi-persistently scheduling isreceived. Hence, the data of a semi-persistently scheduled radio bearergetting active (again) is transmitted via dynamically allocatedresources, until a semi-persistent grant reconfigures ((re-)activates)the semi-persistent resource allocation to take into account the data ofthe a semi-persistently scheduled radio bearer getting active (again) byincreasing the grant accordingly (e.g. by yielding a larger transportblock size allowing for the transmission of data from allsemi-persistently scheduled radio bearers (expected to be) generated ina given semi-persistent scheduling interval).

FIG. 11 is exemplarily highlighting the adaptation of thesemi-persistent resource allocation to a semi-persistently scheduledradio bearer (SPS radio bearer) becoming active (again). The exemplarysignaling procedure of FIG. 11 according to one embodiment of theinvention will also be used to outline another aspect of the invention,namely an improved scheduling mechanism typically implemented in a basestation/eNode B based on the additional information on the mobileterminal's/user equipment's status based on the new rules for triggeringand generating buffer status reports and multiplexing data to uplinkresources as outlined herein.

Generally it is to be noted that applying the procedures outlined withrespect to FIG. 5 and FIG. 6 above allows the scheduler (assuming thatit is collocated with the data receiver, e.g. the base station/eNode B)may draw several conclusions from the signaling behavior of the datatransmitter (e.g. mobile terminal). For example, if semi-persistentresource allocation is activated, the buffer status reports will onlyreport on radio bearers that are not considered in the currentsemi-persistent resource allocation. Hence, the scheduler can be surethat no semi-persistently scheduled radio bearer that is considered inthe current semi-persistent grant will be indicated in the buffer statusreport.

Furthermore, in case there is any reporting on a semi-persistentlyscheduled radio bearer in the buffer status report (e.g. a logicalchannel group to which all a semi-persistently scheduled radio bearersare assigned to is reported on) or by monitoring the content oftransport blocks on dynamically allocated resources, the scheduler mayfurther identify that a semi-persistently scheduled radio bearer hasbecome active (again) (when monitoring the uplink transport blocks, thescheduler even knows which of the semi-persistently scheduled radiobearer has become active), and may reconfigure the semi-persistentresource allocation accordingly, e.g. by a so-called reactivation, so asto have the data transmitter transmitting data of this semi-persistentlyscheduled radio bearer on the semi-persistently allocated resources.Similarly, when monitoring also the content of transport blocks onsemi-persistently allocated resources, the scheduler can also detect asemi-persistently scheduled radio bearer becoming inactive again (e.g. atalk-spurt of a VoIP service ends) and may likewise reduce thesemi-persistent grant to account only for the remainingsemi-persistently scheduled radio bearer(s). Hence, the transport blocksize allocated by semi-persistently scheduling may be varied based onthe additional information obtained from the new procedures fortriggering and transmitting buffer status reports and for multiplexingdata to transport blocks according to the allocation type.

In FIG. 11, essentially a similar scenario as in FIG. 10 is highlighted.It is assumed that VoIP bearer “2^(nd) RB” is becoming active at sometime instance, where semi-persistent scheduling is activated andaccounts for active VoIP bearer “1^(st) RB”. As in FIG. 10, upon arrivalof new data of VoIP bearer “2^(nd) RB” in the transmission buffer, abuffer status report is triggered and the user equipment sends ascheduling request (PUCCH(SR)) on the next available allocated time slotwhere a PUCCH is configured. The eNode B receiving the schedulingrequest allocates a dynamic resource to the user equipment by signalinga dynamic grant on a PDCCH (PDCCH (DG)). The user equipment transmitsthe buffer status report and data of VoIP bearer “2^(nd) RB” on theallocated dynamic resource to the e Node B. From the status report (andoptionally from identifying from which radio bearer(s) the data in thetransport block originate) the eNode B can conclude that VoIP bearer“2^(nd) RB” (as there are two VoIP bearers configured for the userequipment and VoIP bearer “1^(st) RB” is already considered in thesemi-persistent resource allocation). Accordingly, the scheduler of theeNode B may decide to increase the semi-persistent grant such that dataof both VoIP bearers configured in the user equipment can be transmittedon the semi-persistently allocated resource. Hence, the eNode B sendsanother activation (i.e. reactivation) of semi-persistent schedulingyielding the new increased semi-persistent grant, respectively transportblock size to the user equipment (PDCCH (SPS)).

The user equipment receives the new semi-persistent grant and mayconclude (e.g. from the fact that data of VoIP bearer “2^(nd) RB” havingbeen send on a dynamic resource before and/or based on the increasedtransport block size matching the average size of data generated by VoIPbearer “1^(st) RB” and VoIP bearer “2^(nd) RB” within the SPS allocationinterval) that VoIP bearer “2^(nd) RB” is now also considered in thesemi-persistent resource allocation. Accordingly, upon new data of VoIPbearer “1^(st) RB” or VoIP bearer “2^(nd) RB” arriving in thetransmission buffer after reactivation of the semi-persistent resourceallocation, this data will not trigger any buffer status report andscheduling request. Instead, the data of both VoIP bearers is nowtransmitted on the reconfigured semi-persistent resources.

In one further exemplary embodiment, the example given above withrespect to FIG. 11 is further improved in that the scheduler will notchange semi-persistent resource allocation in response to asemi-persistently scheduled radio bearer becoming active right away.This may be beneficial, if the service conveyed by the semi-persistentlyscheduled radio bearer can be assumed to deliver a quite regular bitrate with low deviation from the mean bit rate (i.e. relatively constantpacket sizes in regular intervals) after some time of operation. Oneexample for such type of service is a VoIP service (using IP headercompression), where the IP packet size can be assumed to reach a steadystate after header compression has properly parameterized and that theIP packets are generated in nearly regular intervals, so that overall aconstant bit rate is reached. In this case, the scheduler may allocatedata of the semi-persistently scheduled radio bearer conveying suchservice on dynamic resources, until the data size (number of bits) persemi-persistent scheduling interval is entering a steady state. Uponsuch steady state being reached, the scheduler may then reactivate thesemi-persistent resource allocation with an transport block size(respectively semi-persistent grant) increased according to the steadystate data size of the semi-persistently scheduled radio bearergenerated within a semi-persistent scheduling interval.

In the example given with respect to FIG. 11, the association of the(re-)activation of semi-persistent scheduling with VoIP bearer “2^(nd)RB” has been simple, as VoIP bearer “2^(nd) RB” is considered the onlysemi-persistently scheduled radio bearer that became active (again) andthat transmitted data via dynamic resources. Accordingly, the userequipment has been able to identify in a simple manner that the(re-)activation of semi-persistent scheduling has been in reaction toVoIP bearer “2^(nd) RB” becoming active. However, if there is yetanother VoIP bearer that is getting active (again) before there(re-)activation of the semi-persistent resource allocation occurs, itshould be clear on which VoIP bearer the reactivation of thesemi-persistent resource allocation has impact. If two VoIP bearers havebecome active (and data of these bearers has been transmitted on dynamicresources prior to re-activation), the user equipment should be able tofind out to which of the VoIP bearers that became active there-activation of the semi-persistently scheduled resources pertains.

In a further embodiment of the invention, the user equipment may forexample obey the rule of always linking the next (re-)activation of thesemi-persistent resource allocation to the last semi-persistentlyscheduled bearer that entered the state of waiting for the SPSreactivation in order to have its data transmitted on thesemi-persistently allocated resources. In another embodiment of theinvention, the user equipment assume that a (re-)activation ofsemi-persistent scheduling by means of a semi-persistent grant alwaysconsiders all semi-persistently scheduled bearer that became active (andthose that have been already considered in the previously validsemi-persistent grant).

In an alternative embodiment, the user equipment may also try todetermine to which radio bearer or radio bearers the (re-)activation ofthe semi-persistent resource allocation pertains. Typically, the(re-)activation of the semi-persistent resource allocation to considerone or more further semi-persistently scheduled radio bearer will leadto an increased transport block size being allocated to the userequipment. As the user equipment (as the data source) is also aware ofthe bit rate of each of the services, it also knows the data size perSPS interval that should be considered in the transport block size fortaking into account a respective bearer. Accordingly, in the exampleabove, the user equipment could for example determine the amount of bitsthe transport block size has been increased in comparison to thepreviously valid semi-persistent grant and can conclude from thisdifference, whether it corresponds to the data size per SPS interval ofone or both of the two VoIP bearers that have become active. Based onthis finding, the user equipment could conclude on the VoIP bearer orVoIP bearers considered in the (re-)activation of the semi-persistentresource allocation.

To highlight the allocation of semi-persistent resource over time(respectively the allocated transport block size (TBS)), an exemplaryscheduling for two semi-persistently scheduled radio bearers accordingto an exemplary embodiment of the invention by a eNode B (comprising thescheduler) is described in the following with respect to FIG. 12. Thetwo semi-persistently scheduled radio bearers are referred to as 1^(st)SPS RB and 2^(nd) SPS RB in FIG. 12. Initially, the first VoIP bearer(1^(st) SPS RB) is set up. This may be for example realized byconventional RRC signaling. The set up procedure may be enhanced in thatthe allocation of the VoIP bearer to a predetermined logical channelgroup for semi-persistently scheduled radio bearers is included to theradio bearer setup message, respectively an indication could be added tothis message to inform the user equipment that the radio bearer issuitable for semi-persistent scheduling. As data of the VoIP bearer ispotentially subject to semi-persistent scheduling, the eNode B mayfurther configure the semi-persistent resource allocation but may notyet activate same, as no data of the first VoIP bearer (1^(st) SPS RB)is transmitted yet.

Upon the first VoIP bearer (1^(st) SPS RB) starting to generate datathat is transmitted via dynamically allocated resources first, the eNodeB may decide to activate semi-persistent scheduling (potentially with anew semi-persistent grant matching the data rate of the first VoIPbearer (1^(st) SPS RB). Until activation of semi-persistent schedulingfor the first VoIP bearer (1^(st) SPS RB), the data of the first VoIPbearer may trigger a buffer status report and are considered in thebuffer status report. When activating semi-persistent scheduling, dataof the first VoIP bearer (1^(st) SPS RB) do no longer trigger a bufferstatus report and are not considered in the buffer status report. Ifactivating semi-persistent scheduling, the TBS of the semi-persistentresource allocation is set to TB₁ by the network.

Upon having activated the semi-persistent resource allocation a secondVoIP bearer (2^(nd) SPS RB) is set-up. Again, the user equipment may beinformed on second VoIP bearer (2^(nd) SPS RB) being also suitable forsemi-persistent scheduling during radio bearer setup. When the secondVoIP bearer (2^(nd) SPS RB) starts generating data, same is firsttransmitted via dynamic resources as the semi-persistent resourceallocation has not yet taken into account the data of the second VoIPbearer (2^(nd) SPS RB)—SPS TBS is still TB₁. Accordingly, the data ofthe second VoIP bearer (2^(nd) SPS RB) may trigger a buffer statusreport and are also reported in same.

As described above, the scheduler of the eNode B may decide to allocatesecond VoIP bearer (2^(nd) SPS RB) on a semi-persistent basis andtherefore (re-)activates semi-persistent scheduling sending a grant nowindicating a TBS of TB₂ which is matching the data size TB₁ generated bythe first VoIP bearer (1^(st) SPS RB) and the data size TB₂−TB₁=TB₃generated by the second VoIP bearer (2^(nd) SPS RB) in an SPS interval.The user equipment detects that TB₂ is matching the data size of bothVoIP bearers and concludes that both VoIP are now considered in thesemi-persistent resource allocation. Accordingly, from this point intime new data of the second VoIP bearer (2^(nd) SPS RB) will not triggerany buffer status report and are no longer considered in the bufferstatus reports.

In FIG. 12, the gradient of the rectangles indicating the portions ofthe TBS “stemming” from the first VoIP bearer (1^(st) SPS RB) and thesecond VoIP bearer (2^(nd) SPS RB) is intended to indicate a decrease ofthe data rate of a respective bearer over time (e.g. if a talk spurtends). For example, the eNode B detects that the first VoIP bearer(1^(st) SPS RB) is no longer generating data and may decide to usedynamic scheduling for the first VoIP bearer (1^(st) SPS RB). Therefore,the eNode B may again (re)-activate semi-persistent scheduling byallocating a TBS of TB₃ to thereby only account for the second VoIPbearer (2^(nd) SPS RB) in the semi-persistent resource allocation.Accordingly, new data of the first VoIP bearer (1^(st) SPS RB) may nowagain trigger buffer status reports and are reported in buffer statusreports to the eNode B. As first VoIP bearer (1^(st) SPS RB) is assumedto become active again, the eNode B may decide to schedule the bearer ona semi-persistent basis and once again (re)-activate semi-persistentscheduling by allocating a TBS of TB₂ to account for both VoIP bearers.Thereupon, it is further assumed that both VoIP bearers become inactiveso that finally the eNode B decides to deactivate semi-persistentscheduling. Upon deactivation of semi-persistent scheduling, the VoIPbearers are essentially treated as dynamically scheduled bearers and maytherefore trigger buffer status reports and their data gets reported inthe buffer status reports.

It should be noticed that throughout this document this invention isdescribed with the assumption that semi-persistent resource allocationhas been considered where there is a radio resource allocated on asemi-persistent basis with a given periodicity (SPS interval) configuredfor a communication node—this is also referred to as one SPS pattern.However, the concepts of the invention are still applicable, if multipleSPS patterns are available to the communication node, i.e. there aredifferent SPS intervals defined which may each have a respectivesemi-persistent grant (when activated). In this case semi-persistentlyscheduled radio bearers could be bound to a specific SPS pattern. Theconcepts of the invention as described herein may be applied per SPSpattern to all the semi-persistently scheduled radio bearers.

Furthermore, the in some embodiment of the invention, the concepts ofthe invention have been described with respect to an improved 3GPP LTEsystem, where there is one component carrier configured on the airinterface. The concepts of the invention may also be equally applied toa 3GPP LTE-Advanced (LTE-A) system presently discussed in the 3GPP.

Another embodiment of the invention relates to the implementation of theabove described various embodiments using hardware and software. It isrecognized that the various embodiments of the invention may beimplemented or performed using computing devices (processors). Acomputing device or processor may for example be general purposeprocessors, digital signal processors (DSP), application specificintegrated circuits (ASIC), field programmable gate arrays (FPGA) orother programmable logic devices, etc. The various embodiments of theinvention may also be performed or embodied by a combination of thesedevices.

Further, the various embodiments of the invention may also beimplemented by means of software modules, which are executed by aprocessor or directly in hardware. Also a combination of softwaremodules and a hardware implementation may be possible. The softwaremodules may be stored on any kind of computer readable storage media,for example RAM, EPROM, EEPROM, flash memory, registers, hard disks,CD-ROM, DVD, etc.

It should be further noted that the individual features of the differentembodiments of the invention may individually or in arbitrarycombination be subject matter to another invention.

It would be appreciated by a person skilled in the art that numerousvariations and/or modifications may be made to the present invention asshown in the specific embodiments without departing from the spirit orscope of the invention as broadly described. The present embodimentsare, therefore, to be considered in all respects to be illustrative andnot restrictive.

The invention claimed is:
 1. A method implemented in a mobilecommunication system including a mobile terminal and a base station, themethod comprising: the base station transmitting to the mobile station asemi-persistent scheduling configuration via physical downlink controlchannel (PDCCH) signaling; the mobile terminal receiving from the basestation the semi-persistent scheduling configuration via the PDCCHsignaling; when semi-persistent scheduling is not activated, the mobileterminal transmitting to the base station a scheduling request torequest uplink resources for uplink transmission including uplinktransmission of a buffer status report; when semi-persistent schedulingis activated, the mobile terminal checking a setup information elementof a logical channel as part of a buffer status reporting procedure todetermine whether to trigger a scheduling request for the logicalchannel; when the mobile terminal determines to trigger the schedulingrequest, the mobile terminal transmitting the scheduling request to thebase station for the logical channel; and when the mobile terminaldetermines not to trigger the scheduling request, the mobile terminalnot transmitting the scheduling request to the base station; wherein themobile communication system is selectively operable in one of at least adynamic scheduling mode, in which radio resources are dynamicallyallocated by dynamic grants, and a semi-persistent scheduling mode, inwhich radio resources are allocated on a semi-persistent basis bysemi-persistent scheduling grants.
 2. The method according to claim 1,wherein the setup information element of the logical channel indicatesthat a buffer status report is not triggered.
 3. The method according toclaim 2, wherein the setup information element of the logical channelindicates that the buffer status report is not triggered despite thatdata has become available for the logical channel.
 4. The methodaccording to claim 2, wherein the setup information element of thelogical channel indicates that the buffer status report is not triggereddue to activation of the semi-persistent scheduling.
 5. The methodaccording to claim 1, wherein the mobile terminal determines to triggerthe scheduling request when the setup information element of the logicalchannel indicates activation of the semi-persistent scheduling.
 6. Themethod according to claim 1, wherein the mobile terminal determines totrigger the scheduling request when the setup information element of thelogical channel indicates that data has become available for the logicalchannel.
 7. The method according to claim 1, further comprising: whensemi-persistent scheduling is not activated, no uplink resources areallocated for a transmission time interval, and a buffer status reporthas not been triggered, the mobile terminal transmitting to the basestation the scheduling request to request uplink resources for uplinktransmission of a buffer status report.
 8. The method according to claim1, further comprising: the mobile terminal considering an activationstatus of semi-persistent resource allocation to determine whether totrigger the buffer status report.
 9. The method according to claim 1,further comprising: the mobile terminal considering a scheduling modestatus to determine on which logical channel to report in the bufferstatus report.
 10. The method according to claim 9, wherein thescheduling mode status is an activation of the semi-persistentscheduling or a deactivation of the semi-persistent scheduling.
 11. Amobile communication system comprising: a base station configured totransmit a semi-persistent scheduling configuration via physicaldownlink control channel (PDCCH) signaling, and a mobile terminalincluding: a receiver configured to receive the PDCCH signalingincluding the semi-persistent scheduling configuration, a controllerconfigured to cause the mobile terminal to selectively operate, based onthe PDCCH signaling, in one of at least a dynamic scheduling mode, inwhich radio resources are dynamically allocated by dynamic grants, and asemi-persistent scheduling mode, in which radio resources are allocatedon a semi-persistent basis by semi-persistent scheduling grants, and atransmitter configured to transmit a scheduling request to the basestation to request uplink resources for uplink transmission includinguplink transmission of a buffer status report, wherein the controller ofthe mobile terminal is configured to: when semi-persistent scheduling isnot activated, cause the transmitter to transmit the scheduling request,when semi-persistent scheduling is activated, check a setup informationelement of a logical channel as part of a buffer status reportingprocedure to determine whether to trigger a scheduling request for thelogical channel, when determining to trigger the scheduling request,cause the transmitter to transmit the scheduling request for the logicalchannel, and when determining not to trigger the scheduling request, notcause the transmitter to transmit the scheduling request.
 12. The mobilecommunication system according to claim 11, wherein the setupinformation element of the logical channel indicates that a bufferstatus report is not triggered.
 13. The mobile communication systemaccording to claim 12, wherein the setup information element of thelogical channel indicates that the buffer status report is not triggereddespite that data has become available for the logical channel.
 14. Themobile communication system according to claim 12, wherein the setupinformation element of the logical channel indicates that the bufferstatus report is not triggered due to activation of the semi-persistentscheduling.
 15. The mobile communication system according to claim 11,wherein the controller of the mobile terminal determines to trigger thescheduling request when the setup information element of the logicalchannel indicates activation of the semi-persistent scheduling.
 16. Themobile communication system according to claim 11, wherein thecontroller of the mobile terminal determines to trigger the schedulingrequest when the setup information element of the logical channelindicates that data has become available for the logical channel. 17.The mobile communication system according to claim 11, wherein thecontroller of the mobile terminal causes the transmitter to transmit tothe base station the scheduling request to request uplink resources foruplink transmission of a buffer status report, when semi-persistentscheduling is not activated, no uplink resources are allocated for atransmission time interval, and a buffer status report has not beentriggered.
 18. The mobile communication system according to claim 11,wherein the controller of the mobile terminal considers an activationstatus of semi-persistent resource allocation to determine whether totrigger the buffer status report.
 19. The mobile communication systemaccording to claim 11, wherein the controller of the mobile terminalconsiders a scheduling mode status to determine on which logical channelto report in the buffer status report.
 20. The mobile communicationsystem according to claim 19, wherein the scheduling mode status is anactivation of the semi-persistent scheduling or a deactivation of thesemi-persistent scheduling.